OG239(新的)

239. Organized in 1966 by the Fish and Wildlife Service, the Breeding Bird Survey uses annual roadside counts along established routes for monitoring of population changes of as many as. or of more than 250 bird species, including 180 songbirds.

(A)  for monitoring of population changes of as many as, or of

(B)  to monitor population changes of as many, or

(C)  to monitor changes in the populations of

(D)  that monitors population changes of

(E)   that monitors changes in populations of as many as, or

C is the best choice. The phrase to monitor changes is idio­matic as a statement of purpose ([in order] to monitor), and the intended meaning is expressed concisely and accurately. Neither A nor B produces the idiomatic phrase "... as many as, or more than, 250 ..."--a phrase that would be needlessly wordy here. Also, for monitoring of in A is less concise and idiomatic than to monitor, and population changes in B is less precise than changes in population. In D and E, the pronoun that has no singular noun (required by the verb monitors) to which it can logically or grammatically refer. Survey already has its verb in uses, and no other noun can perform the action of monitors.

问题: C中的population 用复数是不是没有错.它和单数形式有什么区别.

请NN指点.

the populations of more than 250 bird species

Each species has its own population.