New research has found that those who work 11 hour days or

[单选题] New research has found that those who work 11 hour days or more increase their chance of a heart attack by two thirds. If you're about to embark on your usual 12-hour day at the office, you might want to pause a while-a few hours, actually. A study has found that those who spend more than 11 hours at work increase their chance of having a heart attack by two thirds. The team from University College London looked at more than 7,000 civil servants working in Whitehall over a period of 11 years and established how many hours they worked on average a day. They also collected information including the condition of their heart from medical records and health checks. Over the period, a total of 192 had suffered a heart attack. Then the study was published in the joumal Annals of Internal Medicine, reporting that those who worked more than 11 hours a day were 67 percent more likely to have one than those who had a "nine to five" job. Professor Mika Kivimki, who led the study, said:"We have shown that working long days is associated with a remarkable increase in risk of heart disease. Considering that including a measurement of working hours in a GP interview is so simple and useful, our research presents a strong case that it should become standard practice. This new information should help improve decisions regarding medication for heart disease." "It could also be a wake-up call for people who over-work themselves, especially if they already have other risk factors," Professor Kivimki added. Around 2.6 million Britons have heart disease, where the organ's blood supply is blocked by the build-up of fatty deposits in the coronary arteries (冠状动脉). It is the nation's biggest killer, claiming 101,000 lives in this country every year. Heart attacks occur when a coronary artery becomes completely blocked; if the blood supply is not restored, the section of the heart being supplied by the artery will die.

The Passage mainly discusses ________.

A. how does the heart attacks occur
B. the experiment on heart disease
C. more and more people are suffering from heart attack
D. long time working increases the risk of heart disease