David said that it was because of his strong interest in literature he chose the course.

问题补充：

David said that it was because of his strong interest in literature he chose the course.

A. that

B. what

C. why

D. how

答案：

(答案→)A. that

B. what

C. why

D. how

解析：A 考察强调句型。本句是强调句式: It was… that…；强调的是原因状语because of his strong interest in literature,故A正确。