Please answer the following question: The research tracked the health of 101,000 US nurses over three decades. Light-to-moderate smokers were twice as likely to die of sudden heart problems as those who had never smoked. But those who quit smoking saw their risk begin to go back down within years, a journal of the American Heart Association reports. _ During the study, there were 315 sudden cardiac deaths ----where the heart unexpectedly stops working. In people aged 35 or younger, this usually because of a heart condition that runs in the family. But in people who are older than this--as most of the nurses in the study were --it can be the first sign of coronary heart disease, where the heart's arteries become blocked by fatty deposits. Of the 315 sudden deaths in the study, 75 were among current smokers, 148 were among recent or past smokers and 128 occurred in people who had never smoked. Reason to quit After taking into account other heart risk factors, such as high blood pressure, high cholesterol and family history of heart disease, Dr Roopinder Sandhu and his colleagues found the women who smoked were twice as likely as likely to die suddenly even if they smoked "light-to-moderate" amounts --between one and 14 cigarettes a day. For every five years of continued smoking, the risk went up by 8%. But women who quit saw their risk fall to that of someone who had never smoked, after 20 years of cessation. Dr Sandhu, of the University of Alberta, Canad, said: "What this study really tells women is how important it is to stop smoking. The benefits in terms of sudden cardiac death reduction are there for all women, not just those with established heart disease." "It can be difficult to quit. It needs to be a long-term goal. It's not always easily achievable and it may take more than one attempt." Ellen Mason, senior cardiac nurse at the British Heart Foundation, said: "This study shows that smoking just a couple of cigarettes a day could still seriously affect your future health." "As we approach the new year, many of us will be making... Which of the following is best suitable for the blank in the passage? A) Raised risk B) Ways of quitting smoking C) Diseases related to smoking D) Signs of heart disease
A:
A