You can prevent the spreading of communicable disease by following through with Option C) avoiding sharing personal items, like toothbrushes. All of the other options can lead you to getting a disease, if you ignore hygiene you will never be clean, and if you avoid insect repellent you might get a disease from a bug, and if you cough/sneeze without covering your nose/mouth then you may catch a cold. Therefore pointing to the correct answer option C.
D, stalking. They did not have sex, so it is not A or C. He did not hit or touch her, so it is not assault. He did follow her and harass her, though, so he stalked her.
