Final answer:
Ronald exhibited self-control when he waited for his parents to leave the room before opening the jar to get a cookie.
Step-by-step explanation:
Ronald exhibited self-control when he waited for his parents to leave the room before opening the jar to get a cookie. Self-control refers to the ability to regulate one's emotions, thoughts, and actions. In this situation, Ronald resisted the temptation to take a cookie while his parents were still present.