help, pls, my friends, with this question

Even though more money was removed out of stock fund in July /as in any month since October 1987, sales of fund shares in July were not as low as /an industry trade group had previously estimated.

a,
b,
c,
d, than in any month since October 1987, sales of fund shares in July were not as low as
e, than in any other month since October 1987, sales of fund shares in July were not as low as what

OA is e, but what wrong with "as low as" in d,

best regards