If You Join the American Association of Retired Persons (AARP)

If you join the American Association of Retired Persons (AARP) now, the mailing reads, you will receive this free bag, perfect for the traveling you can do more of with member lodging discounts.Meanwhile, the National Rifle Association (NRA) will offer free accidental death and dismemberment insurance if you join today.Both will send you a members-only magazine. Why do the AARP and the NRA, like many other interest groups, offer such benefits and gifts?

A) They are both likely troubled, with declining membership.
B) Their overhead costs are likely increasing with inflation, requiring them to find more members.
C) They are trying to overcome the free-rider problem, which can hit larger interest groups harder.
D) The NRA and the AARP are primarily for-profit operations, with nonprofit lobbying interest-group arms.