## Core Concept
The question pertains to the lifespan of different types of cells or components within the human body, specifically focusing on blood cells. Understanding the lifespan of various blood components is crucial in hematology and internal medicine.

## Why the Correct Answer is Right
The correct answer, **D. RBC (Red Blood Cells)**, has a relatively long lifespan compared to other blood components. Mature red blood cells circulate for about 120 days. After this period, they are removed from the circulation, primarily by the spleen, and recycled.

## Why Each Wrong Option is Incorrect
- **Option A:** Platelets have a short lifespan of approximately 8 to 12 days. They are crucial for blood clotting and are continuously produced in the bone marrow.
- **Option B:** Neutrophils, a type of white blood cell, have a short lifespan of about 5 to 6 days, although their production and turnover are rapid.
- **Option C:** Lymphocytes can have highly variable lifespans, ranging from a few hours to several years or even a lifetime, depending on their subtype and function. However, they generally do not have as fixed or as long a lifespan as red blood cells.

## Clinical Pearl / High-Yield Fact
A key point to remember is that red blood cells (RBCs) live for approximately 120 days. This lifespan is critical for understanding various hematological disorders and the turnover rate of blood components. For example, conditions like hemolytic anemia involve the premature destruction of RBCs, leading to a reduced lifespan.

## Correct Answer: D. RBC (Red Blood Cells).