C is the best answer to this question. There is no need to ride the school bus going to school anymore when the school is within walking distance of the student’s home. A lot of vehicles contribute to the pollution that is being experienced by people every day. It will always help if people would also get enough exercise.
There was a time when people had no choice but to do more physical activities but the different items that were invented recently made people more sedentary. Making sure that the school is within walking distance can help students walk more. This simple activity can already improve one’s health a lot.