It's is all of the above. Just a little hint for you, when there is the option- all of the above, chances are that's the answer.
The answer is C, he loses consciousness. It is because they had not been getting enough air and passed out.
<span>To get the most use from your exercise, stay in your target heart rate range for at least 20 minutes during an exercise session.</span>
I would say there would be a need to cool down because when your swimming u have to cool down or else your lungs won't be able to take in enough air
