Although laughter --- the room ,she feilt lonely.

答案选c
laughter 虽然是名词但它却是主动形式 例句：
Laughter animated the old man's face, as soon as his son's name was mentioned."
只要一提到他儿子的名字老汉就笑逐颜开.
所以B排除
fill 的用法 sw. be filled with sth. 某地被某物填满
sth. fill sw. 某物被某地填满
这句话的中文意思是 虽然笑声充满了房间,但她仍然感觉孤独.
最后一句话：Trust me !