My English teacher has given me so much help that I really want to do something for him _____. [ ]

A. in return

B. in fact

C. in surprise

D. in turn

Passage One

Which parts of the elephant’s body are NOT used by the passenger in climbing onto the elephant

A．The front part of either leg or the ear.

B．Its front leg and the ear.

C．The backside and the tail.

D．Its back leg and the tusk.