关于比较的问题

hardfish

11. Some psychiatric studies indicate that among distin-
guished artists the rates of manic depression and major
depression are ten to thirteen times as prevalent as in
the population at large.

(A) the rates of manic depression and major depres-
sion are ten to thirteen times as prevalent as in
(B) the rates of manic depression and major depres-
sion are ten to thirteen times more prevalent
than in
(C) the rates of manic depression and major depres-
sion are ten to thirteen times more prevalent
when compared to
(D) manic depression and major depression are ten to
thirteen times as prevalent when compared to
(E) manic depression and major depression are ten
to thirteen times more prevalent than in

Key is E. My question is why not use "than that in ..."。 that 指代 manic depression and major depression。

hardfish

Justag, 是哪一篇？我没找到。