Ventricular systole as rising ventricular pressure phase

Steps:

• Recall cardiac cycle: systole is ventricular contraction, marked by sharp pressure rise in ventricles.
• Examine diagram: arrows label pressure curve segments during one cycle.
• Identify systole: arrow over segment where ventricular pressure exceeds atrial and aortic, indicating ejection.
• Confirm: this follows atrial systole and precedes diastole's pressure drop.

Why B is correct:

• B points to the rapid ventricular pressure increase, defining systole as active contraction per cardiac physiology.

Why the others are wrong:

• A indicates atrial systole, with minor atrial pressure rise before ventricular contraction.
• C shows ventricular diastole, with pressure fall and filling.
• D marks isovolumetric relaxation, post-systole pressure drop without volume change.

Final answer: B