## **Core Concept**
Skin grafts are commonly stored at low temperatures to slow down metabolic processes and maintain viability. The storage temperature and duration are critical factors in determining graft survival. Skin grafts can be stored at 4°C, which is a common refrigeration temperature.

## **Why the Correct Answer is Right**
Skin grafts stored at 4°C can survive for up to 21 days. This duration is possible because refrigeration slows down the metabolic rate of the skin cells, thereby preserving their viability. The storage medium and the condition of the graft also play significant roles in determining the survival duration.

## **Why Each Wrong Option is Incorrect**
* **Option A:** 7 days - This is too short; skin grafts can survive longer than 7 days when stored properly at 4°C.
* **Option B:** 14 days - Although skin grafts can survive for 14 days, they can actually survive longer than this.
* **Option D:** 28 days - While some grafts might have extended survival with specific storage solutions, 21 days is a commonly accepted limit for standard storage conditions.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the viability of skin grafts decreases over time, even with proper storage. Therefore, grafting should ideally be performed as soon as possible after procurement. The use of skin preservation solutions can also extend the viable storage period.

## **Correct Answer:** C. 21 days.