请教一道语法题~~~

jingyi011

Organized in 1966 by the Fish and Wildlife Service, the Breeding Bird Survey uses annual roadside counts along established routes ________________more than 250 bird species, including 180 songbirds.
A.for monitoring of population changes of as many as, or o
fB.to monitor population changes of as many, or
C.to monitor changes in the populations of
D.that monitors population changes ofD.that monitors changes in populations of as many as, or


请问b哪里错了？怎么改啊？