问一个从句先行词省略的问题，考试在即，大家帮忙！！

snail007

宾语从句的先行词that
定语从句的先行词that/which/who/whom/whose
同位语从句的先行词 that
名词性从句的what


哪些是可以省略的呢？
我记得只有定语从句的that指代的东西在从句里做宾语的时候可以省，对么？

那么名词性从句的what呢

比如说
Even though more money was removed out of stock funds 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.    as in any month since October 1987, sales of fund shares in July were not as low as
B.    as had been in any other month since October 1987, sales of fund shares in July were not as low as what
C.    than there was in any other month since October 1987, sales of fund shares in July were not as low as that which
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

答案是E
我是根据in any other month推出来的，如果E变成than in any other month since October 1987, sales of fund shares in July were not as low as 也就是说把what省掉是正确的么？

非常感谢！！！

spoiledgirl

白勇里好像说， that which=what, 用后者， 因为更简洁， what 在这里不可省 的， 省了的话than 后面就没有比较对象了