If Melinda's parents wanted her to think about moral judgments at a level higher than she typically uses, their best strategy to encourage her moral development would be to:

a. punish her when she made decisions based on her current level of moral reasoning, so that she would try harder
b. reward her when she made decisions based on her current level of moral reasoning, so she would feel comfortable and be able to advance in her thinking
c. suggest a solution that was at a slightly higher level of moral reasoning so she could think about this
d. simply wait until she gets older, because no kind of coaching or reward can advance the pattern of moral development an individual goes through

c