Which of the following nutritional factors is required for proper collagen assembly in the scar tissue of the 25-year-old woman who sustains a deep, open laceration over her right forearm in a motorcycle accident.

Vitamin C (ascorbic acid) is a powerful, biologic reducing agent that is necessary for the hydroxylation of proline residues in collagen. Vitamin C deficiency (scurvy) causes formation of an abnormal collagen that lacks tensile strength. Patients with vitamin C deficiency exhibit poor wound healing. Dehiscence (bursting open) of previously healed wounds may also occur. None of the other choices are required for collagen assembly.