Final answer:
The upper target heart rate zone for a 23-year-old woman aiming for 80% of her maximum estimated heart rate is approximately 157 beats per minute.
Step-by-step explanation:
To calculate the upper target heart rate zone for a 23-year-old woman aiming for 80% of her maximum heart rate, we first need to determine her maximum heart rate. This can be estimated by subtracting her age from 220 bpm. For a 23-year-old, this would be 220 - 23, which equals 197 bpm. To find 80% of this maximum heart rate, we multiply 197 bpm by 0.80, resulting in approximately 157.6 bpm. Since her resting heart rate is 66 bpm, we do not need to include this in the calculation for her target heart rate during exercise. Therefore, the closest answer to the upper target heart rate zone would be 157 bpm (Option B).