大全140题

140.  As the housing affordability gap widens, middle-income families are especially hard-hit, and these families can no longer qualify to buy homes, and rising rental rates force them to use far more than the standard 25 percent of their incomes for housing, leaving them with no equity or tax write-offs to offset the expenditures.

(A) and these families can no longer qualify to buy homes, and

(B) since these families can no longer afford to buy homes, furthermore

       (C) for these families can no longer afford to buy homes, yet

(D) and these families can no longer afford to buy homes; however,（C）

(E) and these families can no longer afford to buy homes, for

for表示原因，后面能接句子吗？请教一下关于since和for表示原因时的具体用法。

答案选B吗？