OG-13. State officials report that soaring rates of liability insurance have risen to force cutbacks in the operations of everything from local governments and school districts to day-care centers and recreational facilities.
(A) rates of liability insurance have risen to force
(B) rates of liability insurance are a force for
(C) rates for liability insurance are forcing
(D) rises in liability insurance rates are forcing
(E) liability insurance rates have risen to force

In choices A and B, rates of is incorrect; when rates means "prices charged," it should be followed by for.

我怎么没明白它在说什么？到底rate of和for有什么区别啊？

谢谢