I believe that you shouldn't use l<span>ow intensity (light weights) if you want to build muscle mass.
</span>These types of weights won't help you much define the muscles you want to have, as opposed to free weights, weight machines, and high intensity (heavy weights) which definitely will. So if your goal is to build muscle mass, avoid light weights.
I'd say c but I'm not positive
Answer:
Maximum heart rate
Explanation:
The Maximum heart rate is the number of times your heart should beat per minute during physical activity.