i am not good at math.ireally do not donw ___ a.what should i do b.how should i do

C what to do
这里的 I really don't know .宾语从句,用陈述语句排除 a,b.这里的 what to do 相当于What I should do.此外,d 不完整的.
意思：我数学学得不好,我真的不知道我该怎么做