阅读下列短文，从每题所给的四个选项（A、B、C和D）中，选出最佳选项。
Smoking is the worst thing you can do for your health. Fortunately, it’s never too late to get the benefits of quitting. If you’ve tried to quit before and failed, it’s time to make up your mind and try again.
Smoking is responsible for one of every five deaths. That includes 29% of all cancer deaths, 87% of all lung cancer deaths, and nearly 20% of all deaths are from cardiovascular disease. But long before smoking kills you, it ages you. You can see that smoking accelerates the drying and wrinkling of the skin. But there are fewer obvious effects as well. Indeed, smoking takes years away from your life. Nearly half of all chronic smokers die an average of 20 to 25 years before their time.
Besides an early death from cancer or heart disease, smoking can cause lung disorders. People who smoke over a pack a day have almost three times the risk of contracting pneumonia (肺炎) than that of nonsmokers. By lowering levels of estrogen (雌性激素) in men and women, smoking speeds bone less. If a woman smokes a pack of cigarettes every day, she will enter menopause (更年期) with 5% to 10% less bone mass than a nonsmoker.
The good news is that no matter what your age is or how long you’ve smoked, you’ll live longer if you quit today. The Coronary Artery Surgery Study examined nearly 2,000 longterm smokers over the age of 54. Those who quit had significantly lower death rates six years later than those who didn’t. Even the oldest exsmokers had a higher survival rate.
