178- It is explained in the passage that nicotine .................... . A) hits animals more seriously than humans
B) is the only dangerous factor in relation to smoking
C) has a negative effect only upon the arteries
D) is considered by some investigators as one of the reasons why smoking has an adverse effect on
the heart
E) has been considered more dangerous than carbon monoxide for smokers
179- According to the text, studies into the adverse effects of smoking .................... . A) have proved any relationship between smoking and cholesterol levels in humans
B) have illustrated that vitamin D reduces nicotine in the body
