**Core Concept**
Antibody-dependent cell-mediated cytotoxicity (ADCC) is a mechanism of immune response where antibodies bind to specific antigens on the surface of target cells, marking them for destruction. This process involves the activation of immune cells that can recognize and eliminate these marked cells. The main cell involved in this process is a type of white blood cell that plays a crucial role in the innate immune response.

**Why the Correct Answer is Right**
The main cell involved in ADCC is the **Natural Killer (NK) cell**. NK cells are lymphocytes that can recognize and destroy infected cells or tumor cells without prior sensitization. They express Fc receptors that bind to the Fc region of antibodies, allowing them to recognize and engage with cells that have been marked by antibodies. Upon binding, the NK cell releases cytotoxic granules that induce cell death. This process is mediated by the interaction between the Fc receptor on NK cells and the Fc region of antibodies, which is a critical step in ADCC.

**Why Each Wrong Option is Incorrect**
**Option A:** Macrophages are involved in phagocytosis and antigen presentation, but they are not the primary cells involved in ADCC.

**Option B:** T cells are a type of lymphocyte that plays a central role in cell-mediated immunity, but they are not directly involved in ADCC.

**Option C:** B cells are responsible for producing antibodies, but they are not involved in the cytotoxic process of ADCC.

**Clinical Pearl / High-Yield Fact**
NK cells play a crucial role in the innate immune response and are involved in the elimination of infected cells and tumor cells. They are also involved in the regulation of the immune response and can influence the activity of other immune cells.

**Correct Answer: C. Natural Killer (NK) cell.