请教GMAT的一道语法题, 多谢多谢!

In his eagerness to find a city worthy of Priam, the German archaeologist Schliemann cut through Troy and uncovered a civilization a thousand years (older as was the city Homer's heroes knew.)

A.

B. more ancient than the city known to Homer's heroes

C. older than was the city known to Homer's heroes

D. more ancient of a city than Homer's heroes knew

E. older of a city than was the one known to Homer's heroes

答案是 B, 请问C为什么不对, older than 不是更简洁么, 而且比较部分还补全了助动词.