This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Transplantation, Subject name: Surgery
Which of the following are efficient antigen-presenting cells found in the epidermis? 
Select and explain. 
A. Macrophages, B. T cells, C. Langerhans cells, D. Dendritic cells
C: Langerhans cells
Answer: C: Langerhans cells 
Explanation: Processing and presentation of antigen in association with class II molecules is critical for activation of T cells. Langerhans cells are potent antigen-presenting cells (APCs) found in skin. Macrophages are the major APCs in the body. Dendritic cells are APCs found in lymphoid tissue.