**Core Concept**
The question tests the understanding of the changes that occur in stored whole blood over time, focusing on the components or qualities that decrease. This involves knowledge of **hematology** and **transfusion medicine**, including the effects of storage on blood components.

**Why the Correct Answer is Right**
Since the correct answer is not provided, let's discuss a general concept. Typically, the quality of stored whole blood degrades over time due to various factors, including the decrease in **2,3-bisphosphoglycerate (2,3-BPG)** levels, which affect the oxygen-carrying capacity of red blood cells. However, some components like **leukocyte** count might decrease due to storage conditions, but one specific component remains relatively stable or increases: **potassium** levels, as red blood cells leak potassium into the plasma during storage.

**Why Each Wrong Option is Incorrect**
**Option A:** Without the specific option details, we can't provide a direct explanation.
**Option B:** Similarly, without specifics, we can't address why it's incorrect.
**Option C:** And again, lacking the option details, we cannot provide an explanation.
**Option D:** This option would be incorrect based on the premise that most components degrade, but without specifics, it's hard to pinpoint why.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that the storage of whole blood affects its components differently, with some degrading faster than others. Knowing which components remain stable or decrease can be crucial for **transfusion medicine**.

**Correct Answer:** Correct Answer: D. Potassium levels.