A healthy 25-year-old man increases his physical activity level, leading to an increase in venous return to the heart. According to the Frank-Starling mechanism, what is the immediate physiological consequence of this increased venous return?

✓ Correct Answer: Option B

Increased venous return leads to increased end-diastolic volume, which stretches the cardiac muscle fibers. According to the Frank-Starling mechanism, this increased stretch results in a more forceful contraction and thus an increased stroke volume.