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.
The intended meaning of the sentence is to say that Temporary-employment agencies benefit from the Increasing demand for X & from the higher profits made through Y.
Parallelism signal is " Not Only....But Also..."
(A)
the higher profits made when highly paid professionals are placed, requests for whom - Incorrect Parallelism
(B)
the higher profits that are made in the placement of highly paid professionals, requests for whom _ Incorrect Parallelism
(C)
from the requests for highly paid professionals, who make higher profits for the agencies when placed and whose requests - Wrong meaning
(D)
from highly paid professionals,
whose placement makes higher profits for the agencies and whose requests - Wordier
(E)
from the higher profits made in placing highly paid professionals, requests for whom - Concise & maintains parallelism
Answer E.
Thanks,
GyM