Answer:
C. Falling off a sled and breaking his leg.
Step-by-step explanation:
In "the giver", by Lois Lowry, the memory that made Jonas to realize why the chief Elder told him he needed courage, is Falling off a sled and breaking his leg and scraping his face on ice. when Jonas begged the Elder for medicine, He refuses reminding Jonah of the rule.
Jonah was in anguish, his leg arches and he felt lonely. He felt no one else can experience the kind of pain he was going through, at that point he realized what the chief Elder told him that he needed courage. The giver tells him that the pain he is going through gives wisdom, the giver told him that people don't want memories of pain but that the receiver can carry the memories for them.