each NN, question about 885-233

ninishine

233.    According to a study by the Carnegie Foundation for the Advancement of Teaching, companies in the United States are providing job training and general education for nearly eight million people, about equivalent to the enrollment of the nation’s four-year colleges and universities.
(A) equivalent to the enrollment of
(B) the equivalent of those enrolled in
(C) equal to those who are enrolled in
(D) as many as the enrollment of
(E) as many as are enrolled in

The answer is E, I don't understand. Is it because E should be " as many as (those) are enrooled in" ?

200.    Although the bite of brown recluse spiders are rarely fatal, they cause chronic flesh wounds, posing the greatest danger to the infant and elderly, who are particularly vulnerable to its poison.
(A) brown recluse spiders are rarely fatal, they cause chronic flesh wounds, posing the greatest danger to the infant and elderly, who are particularly vulnerable to its
(B) brown recluse spiders are rarely fatal, they cause chronic flesh wounds and pose the greatest danger to the infant and elderly, who are particularly vulnerable to their
(C) the brown recluse spider is rarely fatal, it causes chronic flesh wounds, posing the greatest danger to the infant and elderly, who are particularly vulnerable to their
(D) the brown recluse spider is rarely fatal, it causes chronic flesh wounds and poses the greatest danger to infants and the elderly, who are particularly vulnerable to its
(E) the brown recluse spider is rarely fatal, they cause chronic flesh wounds, posing the greatest danger to the infant and elderly, who are particularly vulnerable to its
answer: E, why C is not right?
In the answer E, what do "they" and "its" refer to?

braveMBA

233. Yes, I agree. However, 'those' could be omitted, a format which brings no error. At the same time, E is the best of the five choices, but not the perfect one.

200. Yes, Why not C? I think E is obviously wrong!