**Core Concept**
T-lymphocytes, also known as T cells, are a type of white blood cell that plays a central role in cell-mediated immunity. They recognize and respond to antigen-presenting cells (APCs) that display peptide fragments on their surface, leading to the activation of T cells and the initiation of an immune response.

**Why the Correct Answer is Right**
The primary function of T-lymphocytes is to recognize and eliminate infected cells or produce chemical signals that activate the immune response. This is achieved through the interaction of T cells with APCs via the T cell receptor (TCR), which recognizes specific peptide fragments presented by major histocompatibility complex (MHC) molecules on the surface of APCs. Activated T cells then proliferate and differentiate into effector T cells, which can perform various functions such as cytokine production, cell-mediated cytotoxicity, or T helper cell functions.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it is not a known function of T-lymphocytes. T cells do not primarily function as antigen-presenting cells.
**Option B:** This option is incorrect as it is not a specific function of T-lymphocytes. While T cells can interact with B cells, this is not their primary function.
**Option C:** This option is incorrect as it is too broad and does not accurately describe the specific function of T-lymphocytes.

**Clinical Pearl / High-Yield Fact**
T cells play a crucial role in controlling viral infections, such as HIV and CMV, and in preventing transplant rejection. A deficiency in T cell function can lead to severe immunodeficiency and increased susceptibility to infections.

**Correct Answer:** C.