—Would you please tell me _____ next?—Think it over.[ ]

—Would you please tell me _____ next?—Think it over.[ ]
—Would you please tell me _____ next?
—Think it over.
[ ]
A.when to do
B.how to do
C.what to do
D.where to do
为什么选c,b不对么

what to do 这是个名词性从句,其中what 是do的宾语
how to do 错在这句子里面还缺一个宾语,应该改成 how to do it.而do是个及物动词是应该接宾语的.