The phrase "a patchy history" in Paragraph 3 refer

单项选择题

Imagine. One day all of us will have to pay for every breath we take. What will that be like Of course, that’s an exaggeration. But as environmental issues grow more concerning, carbon emissions begin costing more and more to businesses and families.
The carbon tax, simply speaking, is an environmental tax charged on fossil fuel. It is based on how much carbon a person or company emits. The primary purpose of such a tax is to lower greenhouse gas emissions. In order to reduce the fees, utilities, business and even individuals attempt to use less energy derived from fossil fuels.
Starting in Europe, carbon tax has had a patchy history. It’s widely accepted in Northern Europe, in countries like Denmark, Finland, the Netherlands, Norway and Poland.
China, as one of the leading carbon emitters, is also considering levying a carbon tax. This would further boost the price of fossil fuel. "We expect China will start to levy various taxes only if they are helpful in mitigating greenhouse emissions and developing a low- carbon economy," Jiang Kejun, a senior researcher with the Energy Research Institute under the National Development and Reform Commission, told China Daily.
"I think a carbon tax is likely to be levied during the 12th Five-Year Plan (2011～2015)," said Jiang.
At last year’s Copenhagen Climate Conference, China promised to cut carbon intensity by 40～45 percent by 2020, from 2005 levels. So the government is carrying out "tougher measures" to realize the green goal.
According to Jiang, China has already passed the stage of "whether to implement" and is planning on "how to implement".
Jiang says that "levying a carbon tax is much more complicated and difficult, especially in the circumstances of China’s economy."
Jiang said it might be more practical for China to make a transition from an energy tax to a carbon .tax, like most European countries have done. Still, the consequence of levying a carbon tax undoubtedly would be beneficial.
"If the rate of carbon tax is 10 yuan/ton of greenhouse gas emission, as advised, and the carbon emission of burning a ton of coal is 2 tons, this means that the price of a ton of coal will be only 20 yuan higher," said Jiang. "The current price of coal is about 600～800 yuan, so, a carbon tax won’t have much effect on the costs of those enterprises."
In the long run, money from levying the carbon tax would be invested in researching and developing new low-carbon energy that can help cut China’s carbon emissions. "Sweden has the highest rate of carbon tax in the world, which is 0.08 euro/kg (0.67 yuan/kg) greenhouse gas," Li Lailai, deputy director of the Stockholm Environment Institute, told Southern Weekly. "Since it’s levied a carbon tax a few years ago, its carbon emission has dropped 3.7 percent from the 1990 level. And its GDP has increased by 25 percent. The numbers tell it all."
Taxation and fiscal incentives are just part of a portfolio of possible policy changes in the future. The ultimate goal is to turn China’s low-carbon development pathway into reality.
"Apart from a carbon tax, the government may begin to levy environmental and resource taxes. Meanwhile, China will greatly boost subsidies to support low-carbon technology research and development," Jiang said.
Suddenly, the word "carbon tax" is coming into our life, even though levying a carbon tax would have a more direct effect on big enterprises than people’s daily life, it’ll still help to better the environment we live in.
Let’s do the math. The U. S. now levies a carbon tariff on products exported to the country. The price is $10～70 (68 ～ 478 yuan) a ton of CO₂. So, take for example the U. S. pop singer Madonna’s latest world tour. It produced 1,635 tons of carbon emissions, thanks to her private jet, tour bus, and the setting up of stage, lights and other machinery. If a carbon tariff is charged at $ 30 (205 yuan) a ton, she has to pay a $49,050 (334, 968 yuan ) carbon tax.
Actress Zhou Xun, an environmental activist, has spent several thousand yuan and bought more than 200 trees to balance out the carbon emission (about 19.5 tons) she produced while traveling last year.
So, it seems that a carbon tax is very much related not just to companies and enterprises, but to every one of us. Spend a thousand yuan, and you can buy trees that can counteract about 5.6 tons of carbon emission. That’s the amount of carbon emissions a Chinese family produces in two years.
In this case, "paying for breath" doesn’t seem to be so far- fetched an idea after all.

The phrase "a patchy history" in Paragraph 3 refers to the fact that ______.

A．the carbon tax is widely accepted in Europe
B．the carbon tax originated from Europe
C．the carbon tax is not levied all over Europe completely
D．Denmark, Finland, the Netherlands, Norway and Poland have accepted the carbon tax for a long time