I believe that you should definitely set your own example by not laughing or deriding that other student. If they do something wrong, you shouldn't laugh at them or mock them, but rather try to help them. What you can do as well is ask that other student nicely to stop deriding other students because of a mistake they may have made.
It is less vivid; "raced after" emits a feeling of either action, suspense, or energy. It allows the reader to connect and fully understand what is going on. "ran after" is vague and emits little high energy.
Answer: B: earths magnetic field protects it from all types of space weather
Explanation: There is no text provided but this is the one that seems like it would be a good summary compared to the other answers.
B would be your best option because it explains the text more.