GWD一道题

CrawlingY

So dogged were Frances Perkins’ investigations of the garment industry, and her lobbying for wage and hour reform was persistent, Alfred E. Smith and Franklin D. Roosevelt recruited Perkins to work within the government, rather than as a social worker.

A.and her lobbying for wage and hour reform was persistent,
B.and lobbying for wage and hour reform was persistent, so that
C.her lobbying for wage and hour reform persistent, that
D.lobbying for wage and hour reform was so persistent,
E.so persistent her lobbying for wage and hour reform, that

我看的一个解释 是：划线部分是一个独立主格，不能有was和and，因为so that结构之间不能有逗号，只能把独立主格和两个逗号都拿掉
我仍然不懂  C为何不对  此题答案为E

赢智

强调的是并列的结构,而且即使是独立主格也应当有BEING