求问"is but one of"

valleywest

With a new park, stadium, and entertainment complex along the Delaware River, Trenton, New Jersey, is but one of a large number of communities that ___ new businesses.
A. is looking to use its waterfront as a way for it to improve the quality of urban life and attract
C.are looking to use their waterfronts to imporve the quality of urban life and attract

Correct answer is C.
is but one of是什么意思?为什么不用is one of???谢谢!!!

neo1001

but在这里是only的意思