Practice question

Pick B: Gas exchange. Thinking about Cardiac Cycle and Regulation in a practical way — what the structure does, or what the process achieves — leads you here. Clinically and academically, the same logic shows up again and again: the functional job described in the stem is exactly what Gas exchange does in Cardiac Cycle and Regulation. Hence Gas exchange is correct. Treat this as a building block for the rest of Cardiac Cycle and Regulation; neighbouring topics often reuse the same principle. Keep a one-line summary card for this idea and revisit it before the paper; short, repeated review beats long cramming sessions.