4The key to the evolution of altruism is that a recipients h

4.The key to the evolution of altruism is that
   a. recipients have to be more likely to carry the altruistic allele than nonrecipients.
   b. actors have to be more likely to carry the altruistic allele than nonactors.
   c. recipients have to be unrelated to the actors.
   d. nonrecipients have to be more likely to carry the altruistic allele than recipients.

Solution

a. recipients have to be more likely to carry the altruistic allele than nonrecipients.