GWD25-5，一个疑问点，请教高人。

For many revisionist historians, Christopher Columbus
has come to

personify devastation and enslavement in the name
of progress that

has decimated native peoples of the Western
Hemisphere.

A.    
devastation
and enslavement in the name of progress that

has decimated native peoples of the Western Hemisphere

B.    
devastation
and enslavement in the name of progress by

which native peoples of the Western Hemisphere

decimated

C.    
devastating
and enslaving in the name of progress those native

peoples of the Western
Hemisphere which in the name of progress are decimated.

D.    
devastating
and enslaving those native peoples of the western

Hemisphere which in the name of progress
are decimated.

E.     
the
devastation and enslavement in the name of progress that

have decimated the native peoples of the Western Hemisphere.

答案是A，主语是devastation and enslavement难道要用单数吗？

小人认为that是修饰progress的

也请NN讲解