**Core Concept**
The underlying principle being tested is the storage duration of blood using **CPD-A (Citrate-Phosphate-Dextrose-Adenine)**, a solution that helps preserve blood by preventing clotting and maintaining the viability of red blood cells.

**Why the Correct Answer is Right**
CPD-A is a commonly used anticoagulant and preservative solution that allows blood to be stored for an extended period. The adenine in CPD-A helps to regenerate **ATP (Adenosine Triphosphate)** in red blood cells, thereby maintaining their viability. This results in a storage life of up to 35 days.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it underestimates the storage duration of blood with CPD-A.
**Option B:** This option is also incorrect as it overestimates the storage duration.
**Option D:** Similarly, this option is incorrect as it does not match the established storage duration.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that the storage duration of blood components can vary significantly depending on the preservative solution used, with CPD-A offering one of the longer storage durations for whole blood.

**Correct Answer:** C. 35 days