A good volunteer should not only display his or her own good image but also see to it _____ the visitor gets the exact information he needs.\x05A.that \x05B.which \x05C.how \x05D.wherewhich one?Why?

A good volunteer should not only display his or her own good image but also see to it _____ the visitor gets the exact information he needs.
\x05A.that \x05B.which \x05C.how \x05D.where
which one?Why?

A
同位语从句

C no why 因为是固定短语