18. Smoke-free environment is a popular issue nowadays.
(A) The attention came from the public awareness of the effects of second-hand smoke.
(B) These effects include an increased risk of heart disease, respiratory disease, and lung cancer.
(C) Therefore, smoke-free laws are enforced in enclosed public places, so people will not suffer fromsecond-hand smoke.
(D) The law prohibits selling cigarettes to minors because smoking will greatly damage their health.