B. is your best answer
have an amazing day! XD
Both Kyla and Tia will be in their zone. Even if they dicrease their heart rates by 20 beats per minute from 175 beats per minute. 155 beats per minute still falls under kyla's target heart rate zone and Tia's target heart rate zone.
For Building Muscle, Getting “Toned,” And Improving How Your Body Looks… Resting 1-3 minutes between sets is probably ideal for you. The higher your training intensity is for a given exercise and/or the more demanding it is on your body, the more you should stay nearer to the 2-3 minute range.