问题：GWD 20-29

Q29:
                A leading figure in the Scottish
                 enlightenment,  Adam Smith’s two major books are to democratic capitalism what Marx’s Das Kapital is to socialism.

1. Adam Smith’s two major books are to democratic capitalism what
2. Adam Smith’s two major books are to democratic capitalism like
3. Adam Smith’s two major books are to democratic capitalism just as

4. Adam Smith wrote two major books that are to democratic capitalism similar to
5. Adam Smith wrote two major books that are to democratic capitalism what

   答案选D，但如果把D项末尾的what换成C项末尾的just as是否更合适？

拜谢~

个人觉得再去研究怎么优化正确答案没有什么意义。