**Core Concept**
The ejection fraction (EF) is a critical parameter of left ventricular function, representing the percentage of blood volume ejected from the left ventricle during systole compared to the end-diastolic volume. It is a key indicator of cardiac performance, often used to assess the effectiveness of the heart's pumping action.

**Why the Correct Answer is Right**
To calculate the ejection fraction, the left ventricular pressure-volume loop is analyzed. The stroke volume (SV) is determined by the difference between the end-diastolic volume (EDV) and end-systolic volume (ESV). The ejection fraction is then calculated as the ratio of stroke volume to end-diastolic volume, expressed as a percentage: EF = (SV / EDV) x 100. This calculation reflects the left ventricle's ability to efficiently pump blood into the circulation.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not a valid calculation for ejection fraction. The formula for ejection fraction involves stroke volume and end-diastolic volume, not the end-systolic volume alone.
**Option B:** This option incorrectly suggests that ejection fraction is calculated as the ratio of end-systolic volume to end-diastolic volume. The correct formula involves stroke volume, not end-systolic volume.
**Option C:** This option is a distractor and does not provide a valid calculation for ejection fraction.

**Clinical Pearl / High-Yield Fact**
When interpreting left ventricular pressure-volume loops, it's essential to consider the relationship between stroke volume and end-diastolic volume. A decrease in stroke volume with a constant end-diastolic volume indicates reduced contractility, while an increase in stroke volume with a constant end-diastolic volume suggests improved contractility.

**Correct Answer:** .