1. Since savings banks have to use short-term deposits to finance long-term fixed-rate mortgage loans, they sometimes lose money when there is a rise in short-term rates and, on the other hand, they are unable to raise the rates on their mortgages.

(A) when there is a rise in short-term rates and, on the other hand, they are unable to raise

(B) when short-term rates rise and they are unable to raise

(C) when a rise in short-term rates occurs and, correspondingly, there is no rise possible in

(D) with a rise in short-term rates, and they are unable to raise（B）

(E) with short-term rates on the rise and no rise possible in

答案为什么是B呢？感觉这里应该有个转折，但是B却用了一个and。请牛牛指点。