whom和them有什么分别?

hedgeforfun

15.    In good years, the patchwork of green fields that surround the San Joaquin Valley town bustles with farm workers, many of them in the area just for the season.
(A) surround the San Joaquin Valley town bustles with farm workers, many of them
(B) surrounds the San Joaquin Valley town bustles with farm workers, many of whom are
(C) surround the San Joaquin Valley town bustles with farm workers, many of who are
(D) surround the San Joaquin Valley town bustle with farm workers, many of which
(E) surrounds the San Joaquin Valley town bustles with farm workers, many are
答案选a,我怎么觉得c好呢?
请解答,谢过先

kathy72

many of them 独立主格结构作伴随状语表目的, 简洁表达名意

many of whom须引导从句, 表达上较累赘, 且改变了句意

gemj

如果要选C，也应该是many of whom.