**Core Concept**
Blood storage with CPD A (Citrate-Phosphate-Dextrose-Adenine) is a method used to extend the shelf life of blood products. This technique involves the use of a preservative solution to prevent blood clotting and maintain the viability of red blood cells.

**Why the Correct Answer is Right**
CPD A is a modified version of the traditional CPD solution, which includes the addition of adenine to prevent the degradation of ATP in red blood cells. This is crucial because red blood cells require a certain level of ATP to maintain their shape, function, and viability. The inclusion of adenine in CPD A helps to maintain the ATP levels in red blood cells, thereby allowing for longer storage periods. This is particularly important for blood products that are intended for transfusion.

**Why Each Wrong Option is Incorrect**
**Option A:** CPD A is not used for storing platelets, as it does not provide the necessary conditions for platelet preservation. Platelets are typically stored in a specialized solution such as SAG-M (Saline-Adenine-Glucose-Mannitol).
**Option B:** CPD A is not used for storing plasma, as it is not necessary to prevent the degradation of clotting factors in plasma.
**Option C:** CPD A is not used for storing whole blood, as it is designed for the storage of red blood cells.

**Clinical Pearl / High-Yield Fact**
The addition of adenine to CPD A is a critical component in maintaining the viability of red blood cells during storage. This is because adenine is converted to ATP, which is essential for maintaining the shape and function of red blood cells.

**Correct Answer: C. Whole blood. Whole blood can be stored with CPD A for a longer period.**