Which of the following statements regarding tobacco use and cardiovascular disease is false?
a. smoking alters the blood-clotting process.
b. the risk of heart attack or stroke is related to the number of cigarettes smoked and the duration of use.
c. smoking effects appear to decrease about 10 years after tobacco use is stopped.
d. environmental (secondhand) tobacco smoke increases risk for cardiovascular disease.

C. Smoking effects appear to decrease about 10 years after tobacco use is stopped

Explanation:

The benefits of quitting smoking are almost instantaneous and can be seen on the same day the individual quits smoking and not 10 years after stopping smoking.

When tobacco is abandoned after 20 minutes, blood pressure and pulse rate are back to normal. After 8 hours, your blood carbon monoxide levels are likely to decrease, and after 24 hours your lungs will function much better.

After 48 hours, nicotine is virtually extinguished from the body, improving some senses such as taste and smell. In the third month, lung function improves, decreasing cough and breathing problems. With a year without a cigarette, the risk of cardiovascular disease is halved, and in 10 years the risk of death from cancer decreases significantly.