## **Core Concept**
The cardiac index is a measure that relates the cardiac output (CO) from left ventricle in one minute to body surface area (BSA), thus relating heart performance to body size. It is calculated using the formula: Cardiac Index (CI) = Cardiac Output (CO) / Body Surface Area (BSA). The normal range for cardiac index is approximately 2.6 to 4.2 L/min/m^2.

## **Why the Correct Answer is Right**
Given that the cardiac output (CO) is 5 liters/min and the body surface area (BSA) is 1.7 m^2, we can calculate the cardiac index as follows: CI = CO / BSA = 5 L/min / 1.7 m^2 = 2.94 L/min/m^2. This value falls within the normal range, indicating that the cardiac output is appropriate for the given body surface area.

## **Why Each Wrong Option is Incorrect**
- **Option A:** If we calculate the value as 2.5 (which could be a distractor), it does not match our calculation of 2.94 L/min/m^2, and it's below the calculated value.
- **Option B:** Similarly, if another option provided a value significantly different from 2.94, such as 3.5 or 4, it would not align with our calculated cardiac index.
- **Option D:** This option would be incorrect based on a miscalculation or incorrect formula application.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the cardiac index helps in assessing the adequacy of cardiac output in relation to the patient's size. It is particularly useful in critical care and when managing patients with heart failure or those requiring intensive monitoring.

## **Correct Answer:** .