大全679，关于比较级的用法

Temporary-employment agencies benefit not only from the increasing demand for clerical workers but also the higher profits made when highly paid professionals are placed, requests for whom have increased in the recent wave of corporate takeovers.
(A) the higher profits made when highly paid professionals are placed, requests for whom
(B) the higher profits that are made in the placement of highly paid professionals, requests for whom
(C) from the requests for highly paid professionals, who make higher profits for the agencies when placed and whose requests
(D) from highly paid professionals, whose placement makes higher profits for the agencies and whose requests
(E) from the higher profits made in placing highly paid professionals, requests for whom

E里面用到比较级higher，可以后面根本没有比较的对象，这样对么？

C为什么不对啊？

不是demand 对应request吗？？？