Which of the following contributes to the unavoidable trade-off between denying aid to some deserving individuals and aiding some undeserving individuals? a. It is costly to identify deserving individuals. b. Undeserving individuals have an incentive to try to appear deserving. c. The “loose reins” principle says that every perfectly designed program will expand, as time passes, to cover too many people. d. Both a and b contribute to the trade-off.