Answer : (b). 105 bpm
Explanation :
given that,
Age = 40 years-old
Resting heart rate = 75 bpm
We know that,
Maximum heart rate = 220- Age
Maximum heart rate = 220-40 = 180 bpm
Heart rate reserve = Maximum heart rate - Resting heart rate
Heart rate reserve = 180 bpm - 75 bpm
Heart rate reserve = 105 bpm
Hence, this is the required solution.
