C. what首先,在what和how中间选。what是修饰名词的,how是修饰形容词的,比如说:how beautiful you are!此句主语是clothes,所以要用what,那后面是they,那就不单单指一件。因为clothes意思就是衣服,是复数形式而已。希望能帮到你~
C