Interest Groups Overcome the Free Rider Problem by Doing All

Interest groups overcome the free rider problem by doing all of the following EXCEPT ______.

A) providing collective goods only to people who join the group
B) providing material benefits only to people who join the group
C) providing solidary benefits only to people who join the group
D) providing expressive benefits only to people who join the group
E) providing selective incentives only to people who join the group