还是GWD

xingxc11

GWD17-Q31:

The agreement, the first to formally require industrialized countries to cut emissions of gases linked to global warming, is a formal protocol by which 38 industrialized countries must reduce emissions of these gases by 2012 or face heavy penalties.

A.by which

B.for which

C.under which

D.such that

E.wherein

答案是C 请问B哪里错了呢？为何选C？望大牛们指导。