大全885-15题，请大家帮我！

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

请问这道题为什么正确答案选A,而不是选C.如果选A,many of them in the area just for the season.是什么成份，谢谢！请指教

C里面many of后面要加whom的.

I. In the United States a significant proportion of the commercial honey supply comes from hobby beekeepers, many of whom are likely to abandon beekeeping with the influx of Africanized bees.
II. Voters in the city, many of whom benefit from the low transit fares, are strongly opposed to increasing local taxes.
III. Saint-Simon’s followers, many of whom were women, based their feminism on an interpretation of his project to reorganize the globe by replacing brute force with the rule of spiritual powers.
IV. The composition of this elite included vice-chancellors, many of whom held office because of their wealth.

A里面many of them是独立主格

大全15. A new phenomenon visible at Managua's major intersections is waves of vendors and beggars, many of them children, who mob cars at the stoplights.
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大全498. The mountainous regions of northern Ethiopia are dotted with hundreds of monasteries, many of them chiseled from solid rock centuries ago.

A of B that+verb句式中的that是不是总是指代A？还是A或B都可以，视具体情况而定？

因为我记得新东方语法有一条貌似说that必须紧跟先行词的。。。

非常感谢！疑问解决了，引经据典，解释的清楚！

怎么视具体情况而定阿？是看句子的语义吗？

看谓语动词的时态就可以看出来，像这句话中

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.

surround明显是修饰的复数名词fields,所以that从句的逻辑主语就是green fields