The correct answer is B. The problem
Explanation
A summary is a short presentation about an event that includes the most important aspects of the event. The summary generally focuses on the exposition of the problem, the development, and the solution of a situation. According to the above, the presented sentence "So, Opal found a dog, and the dog helped her to make friends" is only presenting the problem and the solution without mentioning the problem, which was likely that Opal did not have any friends. According to the above, the correct answer is B. The problem.
