## Core Concept
The lifespan of red blood cells (RBCs) is a critical aspect of transfusion medicine. Normally, RBCs have a lifespan of approximately 120 days in the human body. When RBCs are transfused, their lifespan can be affected by various factors including storage conditions, the age of the cells at the time of transfusion, and the recipient's health status.

## Why the Correct Answer is Right
Transfused RBCs have a maximum lifespan that is generally less than that of native RBCs. Studies have shown that the average lifespan of transfused RBCs is around 60 days, but they can survive up to 120 days. However, the maximum lifespan of transfused RBCs is considered to be approximately 120 days, similar to native RBCs, but with a reduced average survival.

## Why Each Wrong Option is Incorrect
- **Option A:** This option is incorrect because it suggests a very short lifespan, which does not align with the known survival of transfused RBCs.
- **Option B:** This option might seem plausible but does not accurately reflect the maximum lifespan.
- **Option D:** This option suggests a longer or different timeframe that does not correctly represent the maximum lifespan of transfused RBCs.

## Clinical Pearl / High-Yield Fact
A key point to remember is that while the maximum lifespan of transfused RBCs can be up to 120 days, their average survival is typically shorter. This is an important consideration in transfusion medicine, especially for patients requiring chronic transfusions.

**Correct Answer: C. 120 days**