A nurse in a clinic is reviewing the prescriptions for a client who had a delayed hypersensitivity reaction to an unknown trigger. The nurse should expect the provider to prescribe which of the following tests?

A. Blood cultures are used to detect systemic infections, not delayed hypersensitivity reactions. B. A patch test is used to identify allergens causing delayed hypersensitivity reactions (type IV), such as contact dermatitis. C. Urinalysis evaluates kidney and urinary tract conditions, not hypersensitivity reactions. D. Ultrasound is used for imaging internal structures and is not relevant for identifying allergens in delayed hypersensitivity.