I think their probably stressed out about life.
It's probably c because I think it is
Answer:
Muscular Strength and Endurance. Muscular strength and endurance are two important parts of your body's ability to move, lift things and do day-to-day activities. Muscular strength is the amount of force you can put out or the amount of weight you can lift.
Im not quite sure but i would go with
1. changing to a completely new type of activity - overcoming a plateau
2. making your goals easier - restarting after a break
