**Core Concept**
Non-professional antigen presenting cells (APCs) refer to cells that can present antigens to T-cells, but are not part of the professional APC family, which includes dendritic cells, macrophages, and B-cells. These cells are often involved in the presentation of antigens in specific tissue microenvironments.

**Why the Correct Answer is Right**
Non-professional APCs can present antigens to T-cells through a process known as cross-priming, where they engulf and process antigens from other cells and present them on their MHC class I molecules. This is an important mechanism for inducing immune responses in tissues, such as in the skin or lung. Examples of non-professional APCs include epithelial cells, endothelial cells, and fibroblasts.

**Why Each Wrong Option is Incorrect**
**Option A:** Dendritic cells are professional APCs, not non-professional APCs.
**Option B:** Macrophages are also professional APCs, not non-professional APCs.
**Option C:** B-cells can act as professional APCs, especially when presenting antigens to CD4+ T-cells.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that non-professional APCs can present antigens to T-cells through cross-priming, which is an important mechanism for inducing immune responses in specific tissue microenvironments. This is a key concept in understanding the complexities of immune responses and the development of immune-related diseases.

**Correct Answer: D. Fibroblasts.**