on the top of the mountain is an ancient tower dating back to hundreds of years ago .A. T

问题补充：

on the top of the mountain is an ancient tower dating back to hundreds of years ago .

A. To stand

B. Having stood

C. Standing

D. Stand

答案：

A. To stand

B. Having stood

(答案→)C. Standing

D. Stand

解析：地点状语位于句首，句子用完全倒装。故选C。