Sandra's target heart rate zone is 135bpm—172bpm. marissa's target heart rate zone is 143bpm—176bpm. they stop playing basketball and take their pulse, and both count the heart rate at 144bpm. if they decrease their heart rates by 20bpm, who will be in her thr zone?

After exercising, both Sandra and Marissa had a heart rate of 144 bpm.
Now, we will decrease this heart rate by 20 for each one as mentioned and compare to the THR:

1- Sandra:
    Heart rate after decreasing 20 bpm = 144 - 20 = 124 bpm
    Her target heart rate zone is 135 bpm—172 bpm
    Therefore, Sandra will not be in her THR zone

2- Marissa:
    Heart rate after decreasing 20 bpm = 144 - 20 = 124 bpm
    Her target heart rate zone is 143 bpm—176 bpm
    Therefore, Marissa will not be in her THR zone

Ithink it’s d. that should be correct.