They lost their way in the forest, and______made matters worse was that the night began to fall.
【正确答案】 B
【答案解析】解析：本题考查主语从句。句意：“他们在森林中迷了路，更糟糕的是夜幕开始降临了”。名词性关系代词what引导主语从句，what在该主语从句中做主语。that也可以引导主语从句，但that在主语从句中不做任何成分。it不是关系代词，不能引导任何从句。