Critical Reasoning

I.
These days, drug companies and health professionals alike are focusing their attention on cholesterol in the blood. The more cholesterol we have in our blood, the higher the risk that we shall die of a heart attack. The issue is pertinent since heart disease kills more North Americans every year than any other single cause. At least three factors---smoking, drinking, and exercise-can each influence levels of the cholesterol in the blood.


Which one of the following can be properly concluded from the passage?
(A) If a person has low blood cholesterol, then that person's risk of fatal heart disease is low.
(B) Smoking in moderation can entail as great a risk of fatal heart disease as does heavy smoking.
(C) A high-cholesterol diet is the principal cause of death in North America.
(D) The only way that smoking increases one's risk of fatal heart disease is by influencing the levels of cholesterol in the blood.
(E) The risk of fatal heart disease can be altered by certain changes in lifestyle.

anwser: (E)

please help me to identify the C/P/A, and analyse the whole question.
i cannot figure out why A is wrong since it says"The more cholesterol we have in our blood, the higher the risk that we shall die of a heart attack."

II.
Historian: We can learn about the medical history of individuals through chemical analysis of their hair. It is likely, for example, that Isaac Newton's psychological problems were due to mercury poisoning; traces of mercury were found in his hair. Analysis is now being done on a lock of Beethoven's hair. Although no convincing argument has shown that Beethoven ever had a venereal disease, some people hypothesize that venereal disease caused his deafness. since mercury was commonly ingested in Beethoven's time to treat venereal disease, if researchers find a trace of mercury in his hair, we can conclude that this hypothesis is correct.

Which one of the following is an assumption on which the historian's argument depends?
(A) None of the mercury introduced into the body can be eliminated.
(B) Some people in Beethoven's time did not ingest mercury.
(C) Mercury is an effective treatment for venereal disease.
(D) Mercury poisoning can cause deafness in people with venereal disease.
(E) Beethoven suffered from psychological problems of the same severity as Newton's.

the answer is B, which i think is questionable.

III.
how can i improve my pace?
when the question stem is long, i have to spend time comprehanding, and analysing the choices one by one. it is rather time consuming. i am worried that i don't have enough time to finish the verbal.