【题目】Waste tends to be the pollution problem _______ other problems are eventually reduced.
A.of which
B.to which
C.by which
D.through which

【答案】B
【解析】考查定语从句。句意：浪费导致污染问题，其他问题最终也会成为污染问题。 be reduced to“使变弱为……；沦为……”是固定短语。故选B。