Final answer:
The child exposed to non-aggressive role models is most likely to suppress aggression, according to frustration-aggression theory, through constructive coping mechanisms modeled in the community.
Step-by-step explanation:
According to the frustration-aggression theory, the child who is most likely to learn to suppress outward expressions of aggression is C) A child who is exposed to non-aggressive role models in the community. This is because the frustration-aggression theory posits that frustration leads to aggression, and when exposed to non-aggressive role models, the child is less likely to learn and exhibit aggressive behavior. Instead, they witness how to cope with frustration in a constructive way, which can decrease the likelihood of aggression being learned and expressed.