13 A 33-year-old man incurs thermal burn injuries to 40% of his total body surface area in an accidental fire while repairinga fuel storage tank. On physical examination, the skin of the trunk, neck, and face is pink, shows blister formation, and is painful to touch. The skin of the arms is white and anesthetic. Skin grafting is necessary on the arms, but not on other injured areas of skin. Which of the following structures is most likely absent from the sites that required skin grafting? (A) Collagen fibers (B) Dermal appendages 0 (C) Epidermal stratum spinosum (D) Keratin (E) Macrophages (F) Nerves 0