## Core Concept
Cytotoxic T lymphocytes (CTLs), also known as CD8+ T cells, are a type of immune cell that plays a crucial role in cell-mediated immunity. They are capable of inducing the death of infected cells or tumor cells. CTLs recognize antigens presented by MHC class I molecules on the surface of target cells.

## Why the Correct Answer is Right
CTLs exert their cytotoxic effects primarily through the release of cytotoxins, such as perforin and granzymes, which induce apoptosis in target cells. Perforin forms pores in the target cell membrane, allowing granzymes to enter the cell and trigger a cascade of intracellular reactions leading to cell death. This mechanism is critical for eliminating virus-infected cells and tumor cells.

## Why Each Wrong Option is Incorrect
* **Option A:** This option is incorrect because it does not accurately describe the primary function or mechanism of CTLs.
* **Option B:** This option is incorrect as it does not specifically relate to the known functions or characteristics of CTLs.
* **Option D:** This option is incorrect because it does not accurately represent the role or mechanism of action of CTLs in immunity.

## Clinical Pearl / High-Yield Fact
A key point to remember is that CTLs are vital for controlling viral infections and for surveillance against tumor cells. Their dysfunction or deficiency can lead to increased susceptibility to viral infections and cancer.

## Correct Answer: C.