A patient develops a skin rash 48-72 hours after exposure to poison ivy. This reaction is an example of which type of hypersensitivity?

✓ Correct Answer: Option D

Poison ivy dermatitis is a classic example of Type IV hypersensitivity, also known as delayed-type hypersensitivity. This reaction is mediated by T-lymphocytes, specifically CD4+ T helper cells, and macrophages, with symptoms appearing 24-72 hours after antigen exposure.