Critical Reasoning

Scientists have determined that an effective way to lower cholesterol is to eat three servings of whole grains every
day. Studies have shown that the cholesterol levels of people who did so were significantly lower after six months
than were those of people who did not, even though the cholesterol levels of the two groups were the same before
the studies began. Clearly, eating whole grains can have an appreciable effect on cholesterol levels. The answer
to which of the following questions, if true, would be most useful in evaluating the claim about whole
grains above?

a Is it realistic to expect people to eat three servings of whole grains per day?
b Were the two groups of people in the study involved in the same exercise program?
c Can the same drop in cholesterol be achieved through medication?
d Did the study continue to track the subjects beyond six months?
e Are most consumers aware of the different between whole grains and processed grains?

thanks in advance