Much to our relief although we are not that rich our income is now doubleit was five yea

问题补充：

Much to our relief, although we are not that rich, our income is now doubleit was five years ago.

A. that

B. than

C. which

D. what.

答案：

A. that

B. than

C. which

(答案→)D. what.

解析：what引导的表语从句, 此处what相当于 the income that。