紫皮OG11 72

The
gyrfalcon, an Arctic bird of prey, has survived a close brush with
extinction; its numbers are now five times greater than when the use of
DDT was sharply restricted in the early 1970's.

(A) 
extinction; its numbers are now five times greater than

(B) 
extinction; its numbers are now five times more than

(C) 
extinction; their numbers now fivefild what they were

(D) 
extinction; now with fivefild the numbers they had

(E) 
extinction; now with numbers five times greater than

 请问B错在哪里？官方的解释是："The use of more instead of greater inappropriately implies there are now more numbers, rather than more gyrfalcons" 看得比较糊涂

谁能解释下？

greater和more用在比较的地方时区别在哪啊？