**Core Concept**
The activation of naive T cells is a crucial step in the adaptive immune response. This process involves the recognition of antigens by T cell receptors (TCRs) on the surface of T cells, which triggers a cascade of intracellular signaling events leading to T cell activation.

**Why the Correct Answer is Right**
The most potent stimulator of naive T cells is the antigen-presenting cell (APC) displaying the peptide-MHC (pMHC) complex on its surface. This complex is formed when a peptide derived from an antigen is loaded onto a major histocompatibility complex (MHC) class I or II molecule on the surface of the APC. The pMHC complex interacts with the TCR on the surface of the naive T cell, resulting in the activation of the T cell through the engagement of the CD4 or CD8 coreceptor and the co-stimulatory molecules CD28 and CD80/CD86 on the APC.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because while dendritic cells are professional APCs that can stimulate naive T cells, they are not the most potent stimulators.

**Option B:** This option is incorrect because cytokines such as IL-2 and IL-12 can support T cell activation and proliferation, but they are not the primary stimulators of naive T cells.

**Option C:** This option is incorrect because B cells can present antigens to T cells through the process of antigen presentation, but they are not the most potent stimulators of naive T cells.

**Clinical Pearl / High-Yield Fact**
The interaction between the TCR and pMHC complex is a highly specific and tightly regulated process, and any disruption in this process can lead to immune dysregulation and disease.

**Correct Answer:** D.