Many pregnant women suffer from vitamin deficiency, but this is frequently
not due to vitamin deficiency in their diets; most often it is because they
have higher requirements for vitamins than do the rest of the population.

The best criticism of the reasoning in the statement above is that it

a. fails to specify the percentage of pregnant women who suffer from vitamin deficiency
b. gives insufficient information about why pregnant women have higher vitamin requirements than do other groups
c. fails to employ the same reference group for both uses of the term "vitamin deficiency"
d. provides insufficient information about the incidence of vitamin deficiency
in other groups with high vitamin requirements
e. uses "higher requirements" in an ambiguous manner