What is the text revealingA．How to make the corona

单项选择题

There is a great deal of controversy within the medical profession regarding the use and value of the coronary bypass procedure, and for more than eight years the American Heart Association has discussed the question at its regular scientific sessions.
The bypass operation consists of open heart surgery in which the physician takes a vein from the patient’s leg and implants it near the heart to construct a passage around the blockage in a clogged artery so that blood can flow freely by. The operation performed on about 100,000 persons a year in the US and costs approximately $10,000. The procedure is designed to relieve tie pain of angina pectoris which occurs when the blood supply’s obstructed and also to allow the patient more freedom of sustained activity.
In persons with advanced heart disease and blockage in several arteries, the bypass operation is considered by most doctors to be the preferable means of prolonging life. In the case of those with a less advanced disease, or where only one artery is involved, the advisability of the procedure is much more controversial. The operation doesn’t cure the disease that caused the blocked artery
in the first place. According to some studies, somewhere around half of the patients have another blocked artery within five years, and in some cases even within one year.
There is of course a mortality rate in any major operation which varies from physician to physician and hospital to hospital. The danger to the patient is greatly increased if he is in generally poor condition, very advanced in age, or suffering from some serious or debilitating illness. It is essential that the operation be performed by a skilled surgeon knowledgeable about this particular technique and in a hospital with the best possible facilities for his use.

What is the text revealing

A．How to make the coronary bypass operation.
B．An objective introduction of the coronary bypass operation.
C．The controversy within the medical profession on the coronary bypass procedure.
D．A complete refusal of coronary bypass operation