[求助]再次询问GWD-4-13中what的作用

原题：Q41: GWD-4-13

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.

 
A.  Adam Smith’s two
     major books are to democratic capitalism what
B   Adam Smith’s two
     major books are to democratic capitalism like
C   Adam Smith’s two
     major books are to democratic capitalism just as
D   Adam Smith wrote
     two major books that are to democratic capitalism similar to
E   Adam Smith wrote
     two major books that are to democratic capitalism what

这个答案是E，因为D的similar to 明显读了有问题，但是细究一下。请nn具体说下similar to 的语法错误以及E中what的作用，它是什么词性，在这里什么意思哦

惯用句式是：A is to B what C is to D.
            意为“A对B而言正如C对D一样”例如：

Air is to us What water is to fish.  空气对于我们犹如水对于鱼。(介词to 表示两者的关系)

也有“A is for B what C is for D.”句式。例如：

Poultry is for the cook what canvas is for the paint. 厨师离不了家禽正如画家离不开画布一样。（介词for表示“供…使用”）

what 引导的从句也可以放在句首,其句式是: What C is to D, that A is to B.(= A is to B what C is to D.)

在这一结构中，喻体在前，主体在后，相当于“just as...,so...”结构,意思也是“A对B而言正如C对D一样”例如:

What blood vessel is to a man's
        body, that railway is to transportation.（=Just as blood vessel is to a man's body ，so Railway  is to transportation.）

铁路对于运输,好比血管对于人体一样。

Many thanks!

Thanks for your explation.

快乐的异乡人,

谢谢！

终于有个明白人讲清楚了这题！

Thank you so much, NN!