紧急请教GMATPrep一道语法题，总结里好像没有

According to a 1996 study published in Journal Human Resources, Americans of Middle Eastern descent were twice as likely as was the national average to be self-employed.

A. as was the national average to be self-employed

B. as the average Americans to be self-employed

C. as the national average that they would be self-employed

D. to be self-employed than was the average American

E. that they would be self-employed than was the national average

正确答案是B, 但我选的是A。认为A符合了谓语动词和助动词尽量补出的原则。不太清楚这个题的考点主要是什么？

考点是： someone is as likely as someone to do something.

A 的 比较对象不对称，所以错。