单项选择题
A new study reports the common drug aspirin greatly reduces life threatening problems after an operation to replace blocked blood vessels to the heart. More than 800,000 people around the world have this heart surgery each year. The doctors who carded out the study say giving aspirin to patients soon after the operation could save thousands of lives. People usually take aspirin to control pain and reduce high body temperature. Doctors also advise some people to take aspirin to help prevent heart attacks. About 10— 15 percent of these heart operations end in death or damage to the heart or other organs. The new study shows that even a small amount of aspirin reduced such threats. The doctors said the chance of death for patients who took aspirin would fall by 67%. They claimed this was true if the aspirin was given within 48 hours of the operation. The doctors believe aspirin helps heart surgery patients because it can prevent blood from thickening and blood vessels from being blocked. However, the doctors warned that people who have stomach bleeding or other bad reactions from aspirin should not take it after heart surgery.
In what way can aspirin help heart surgery patients according to the doctors() A．Prevent losing blood.
B．Help them keep awake.
C．Help people move blood.
D．Prevent blood from thickening and blood vessels from being blocked.