**Core Concept:**

The core concept being tested in this question is the classification of cells involved in cell-mediated immunity (CMI) and their respective roles in the immune response. CMI is a crucial aspect of the human immune system, involving the activation of immune cells to target and eliminate intracellular pathogens, tumors, and other foreign substances within the host's cells.

**Why the Correct Answer is Right:**

The correct answer, T cells, are a subset of lymphocytes that play a vital role in cell-mediated immunity. They are responsible for recognizing and attacking infected or abnormal cells through a process called clonal selection and activation. T cells are classified into two main types: helper T cells (CD4+) and cytotoxic T cells (CD8+). These cells work together to eliminate infected cells and prevent the spread of infection, thus contributing to the overall health and defense of the host.

**Why Each Wrong Option is Incorrect:**

A. B cells, also known as plasma cells, are responsible for producing antibodies (immunoglobulins) to neutralize extracellular pathogens, not stimulate cell-mediated immunity.

B. Natural Killer (NK) cells are cytotoxic cells involved in the immune response against virus-infected cells and tumor cells, but they do not stimulate CMI.

C. Neutrophils and macrophages are phagocytic cells that play a role in the immune response against pathogens, but they are not directly involved in stimulating cell-mediated immunity.

**Clinical Pearl:**

Understanding the role of different immune cells in various aspects of immunity is crucial for medical professionals. The correct answer, T cells, demonstrate the importance of a thorough comprehension of immune cell types and their functions in maintaining a robust immune response against pathogens and abnormal cells.

**Correct Answer:** D. T cells (CD4+ and CD8+).