Answer:
Many interest groups face the b. free-rider problem when recruiting members who can gain the benefits of their activities whether or not they join.
Step-by-step explanation:
The essence of interest groups is in its desire to fight for a certain change or a policy that brings benefits to the representatives of this group.
Let's take an example of an interest group that advocates for the introduction of benefits for owning electric cars. Among such benefits can the availability of free chargers throughout the city.
While the members of the group all own electric cars and will benefit from this policy, also other people who own electric cars would benefit from this policy, which makes them free-riders. Thus, a potential free-rider is a person owns an electric car and would benefit from the policy whether he/she joins the group or not.