## Core Concept
The stroke volume (SV) is the volume of blood pumped by the left ventricle of the heart in one contraction, or heartbeat. It is a critical component of cardiac output (CO), which is the total amount of blood the heart pumps per minute. Stroke volume is influenced by preload, contractility, and afterload.

## Why the Correct Answer is Right
The correct answer, , states that stroke volume is approximately 70 mL. This is a typical value for a healthy adult at rest. The normal range for stroke volume is about 60-100 mL, and it can vary based on factors such as heart rate, blood pressure, and physical conditioning.

## Why Each Wrong Option is Incorrect
* **Option A:** - This option is incorrect because stating a value without context does not provide enough information to assess its accuracy regarding stroke volume.
* **Option B:** - This option is incorrect because, similar to option A, it lacks context or a specific value to evaluate its correctness.
* **Option C:** - This option might seem plausible but is incorrect if it provides an implausible value for stroke volume, such as being significantly outside the normal range (e.g., 200 mL).
* **Option D:** - This option is incorrect if it suggests a value that is not within the normal range for stroke volume or does not accurately reflect a characteristic of stroke volume.

## Clinical Pearl / High-Yield Fact
A key point to remember is that stroke volume can be estimated using the formula: SV = EDV - ESV, where EDV is the end-diastolic volume (the volume of blood in the ventricle at the end of diastole) and ESV is the end-systolic volume (the volume of blood left in the ventricle after contraction). Factors that increase preload (e.g., increased blood volume) can increase stroke volume, up to a point, according to the Frank-Starling mechanism.

## Correct Answer: . 70 mL.