【正确答案】 B

【答案解析】此题属于语法题。本句是强调句型：It was…that，而不是定语从句，(考生往往会把强调句型误认为定语从句)，故应选[D] that。that 可对句子的任何成分进行强调，例如：It was the film that greatly influenced the young generation．又如：It was in this room that I was born．选项[A] when，选项[C] which 和选项[D] in which 都不用于强调句型；另外一个可以用于强调句型的词是who，对句子的主语进行强调，例如：It was I who called you．