What Is the Difference Between Trustees and Delegates

What is the difference between trustees and delegates?

A) Trustees are seen as agents for the whole society while delegates are seen as agents of their voters.
B) Trustees are seen as agents of the whole population while delegates are seen as representing socially defined groups.
C) Trustees are members of the lower house while delegates typically are members of the upper house.
D) Trustees are fully professionalized members of parliament while delegates are non-professional members.