C. they grow quickly due to the chemicals
Learning how to control their eating
He should increase the speed in which he runs as the faster one runs the faster their heartbeat.
<span>True, because many people are competitive by nature, so they need the challenge of a good competition in order to feel motivated to do the physical activity. If there is no competition, they don't feel compelled to engage in any physical activity. That's why those people tend to choose team sports or other activities in which they have to compete against other participants.</span>
