Final answer:
The wound measurement determined by inserting a sterile applicator at a 90-degree angle to the wound and then marking it even with the skin is the depth of the wound.
Step-by-step explanation:
The wound measurement that is determined by the method of moistening a sterile, flexible applicator with saline, inserting it gently into the wound at a 90-degree angle, marking the point where the applicator is even with the skin, removing the applicator, and measuring with a ruler is the depth of the wound (Option C). This is a common practice in health care to assess the severity of a wound like a stab wound and to determine the appropriate treatment or intervention required. Proper wound measurement is crucial for monitoring progress in healing and identifying potential complications.