Being that she was secretary of labor, Frances Perkins’ considerable influence with Franklin D. Roosevelt was used preventing him from restraining strikes by longshoremen and automobile workers.

A. Being that she was secretary of labor, Frances Perkins’ considerable influence with Franklin D. Roosevelt was used preventing

B. As secretary of labor, Frances Perkins’ considerable influence with Franklin D. Roosevelt was used to prevent

C. Being secretary of labor, Frances Perkins’ considerable influence with Franklin D. Roosevelt was used preventing

D. As secretary of labor, Frances Perkins used her considerable influence with Franklin D. Roosevelt to prevent

E. Secretary of labor, Frances Perkins’ considerable influence was used with Franklin D. Roosevelt preventing

请问如果用答案D的话，那后面的by longshoremen and automobile workers.是修饰谁的呢？？不会是修饰罢工吧？

是的。这里by的意思是：▶WHO/WHAT DOES SOMETHING◀，即longshoremen and automobile workers举行的罢工。