Answer:
D. im pretty sure, it just makes sense
To set your intensity level, you need to use your maximum heart rate, which is determined by subtracting age from 220.
Answer: The answer is Adaption-level Phenomenon
Explanation: Adaption-level phenomenon is a tendency which people have to adapt fast to a new situation until the situation becomes the norm. They get used to such situation such that it is no longer big deal to them anymore and another new experience is needed. If a new situation seems better than the current state the person feels better but only for a little while, if the situation however feels like a step backward, the person becomes sad and frustrated.
