Normal Adult Resting Heart Rate

Steps:

• Identify the context as a typical adult at rest, where heart rate is measured in beats per minute (bpm).
• Recall the medical standard: normal resting heart rate ranges from 60-100 bpm for adults.
• Evaluate options against this range to find the most representative average value.
• Select 80 bpm as the common midpoint example used in physiology.

Why B is correct:

• 80 bpm falls squarely in the 60-100 bpm normal range defined by the American Heart Association for healthy adults at rest.

Why the others are wrong:

• A: 60 bpm is the low end of normal but indicates a highly fit athlete, not typical.
• C: 100 bpm is the upper normal limit but suggests mild tachycardia for resting.
• D: 120 bpm exceeds normal, indicating tachycardia or stress/exercise.

Final answer: B