1. why is running so hard on the body? 2.how can mental alertness prevent injuries?

1. A person who’s running lands on one foot with all of his or her body weight, multiplied two to three times by the forces of gravity and forward momentum. With this kind of hammering, it’s no surprise that injuries occur.

2.Studies have shown that a number of psychological factors might predispose an athlete to an acute injury. If you’re overly “psyched out” by the importance you place on the number of repetitions you can do or the number of games you win, or if the environmental conditions in which you must perform aren’t ideal (“it’s too windy/cold/hot”), your psychological state could detract from your performance and put you at risk for injury. If you’re already injured and are still engaging in activity, this, too, can be a distraction that puts you at greater risk.

Ithink it's choice d (antibiotic resistance)