The argument remains extremely heated it is worthwhile for China to open its door to for

问题补充：

The argument remains extremely heated it is worthwhile for China to open its door to foreign cars.

A. that

B. which

C. if

D. whether

答案：

A. that

B. which

C. if

(答案→)D. whether

解析： whether引导同位语从句，说明名词argument的内容。