Answer:
"It's making me so upset," he responded, explaining that his classmates mocked Melvin for having muddy sneakers.
Step-by-step explanation:
shows that Melvin's main problem is that his classmates are mocking him for having muddy sneakers. This is the main issue that is causing Mello to be upset and is the focus of the article. The other sentences provide context and additional information about the situation, but this sentence specifically highlights Melvin's problem.