英语单选题疑问，请老师帮忙解决

英语单选题疑问，请老师帮忙解决


1。——What should i wear to attend his wedding party?
    --------Dress ___you like.
A.what   B however C whatever   D.how
我认为选C答案是B，，为什么？
2。Would you please give me the basic facts ___you have reduced what the speaker said?
A.by which    Bto which   C.of which D.with which
我认为是C答案是B。不是介词要看先行词吗？？？？？