In recent years, many Americans have become intere

单项选择题

In recent years, many Americans of both sexes and various ages have become interested in improving their bodies. They have become devoted to physical fitness. The need to exercise has almost become compulsive with many, persons who have a strong desire to be, more physically fit. By nature, Americans are enthusiastic and energetic about their hobbies and pastimes. They apply this enthusiasm, and energy to jogging/running. As a result, there are running clubs to join and many books and magazines to read about running. The desire to be physically fit is explained by a "passion" for good health. The high rate of heart attacks in the 1960s caused an increase on the part of the public in improving the human body. Middle-aged men especially suffer from heart attacks. Thus, they are one group strongly interested in more physical exercise. In fact, many doctors encourage their patients to become more physically active, especially those who have sedentary jobs. It is interesting to note that the rate of heart attacks began to decrease in the 1970s and it is still decreasing. Physical fitness currently enjoys a favored role in the United States. It is a new "love" that many Americans have cherished. Will it last long Only time will tell - or until another "new passion" comes along.

In recent years, many Americans have become interested in improving their bodies because _____.

A．they are enthusiastic about their hobbies and pastimes
B．they have a strong desire to be more physically fit
C．there are many running clubs to join
D．there are many books and magazines to read about running