Breathing volume and rate increase with activity level

Steps:

• Measure breathing depth as the amplitude (tidal volume) in each graph.
• Measure breathing rate as the frequency of oscillations per unit time.
• Compute total ventilation as depth multiplied by rate for each graph.
• Compare totals to identify the highest, indicating most activity.

Why B is correct:

• Graph B has the highest tidal volume and respiratory rate product, maximizing minute ventilation per the formula (tidal volume × breaths per minute), which rises with metabolic demand during intense activity.

Why the others are wrong:

• A: Low depth and moderate rate yield minimal total ventilation.
• C: High rate but shallow depth results in lower overall volume than B.
• D: Balanced but moderate depth and rate produce less ventilation than B.

Final answer: B