**Core Concept**
2,3-Bisphosphoglycerate (2,3-DPG) is an organic phosphate that binds to hemoglobin in red blood cells, reducing the oxygen affinity of hemoglobin and facilitating the release of oxygen to tissues. In anemia, the body attempts to compensate for reduced oxygen delivery by increasing the production of 2,3-DPG.

**Why the Correct Answer is Right**
In anemia, the body responds to decreased oxygen delivery by increasing the production of 2,3-DPG. This increase in 2,3-DPG reduces the oxygen affinity of hemoglobin, allowing for more efficient release of oxygen to tissues. The enzyme responsible for producing 2,3-DPG is 2,3-bisphosphoglycerate mutase, which is upregulated in anemia. As a result, the concentration of 2,3-DPG in red blood cells increases, facilitating the release of oxygen to tissues.

**Why Each Wrong Option is Incorrect**
**Option A:** Decreased 2,3-DPG levels would actually worsen anemia by increasing the oxygen affinity of hemoglobin, making it even harder for tissues to receive oxygen.
**Option C:** The statement that 2,3-DPG levels are either decreased or increased is incorrect, as the correct answer is that they are increased.
**Option D:** 2,3-DPG levels are not unchanged in anemia, as the body attempts to compensate for reduced oxygen delivery by increasing production.

**Clinical Pearl / High-Yield Fact**
Remember that 2,3-DPG levels are increased in anemia to compensate for reduced oxygen delivery, and that this increase is mediated by the upregulation of 2,3-bisphosphoglycerate mutase.

✓ Correct Answer: B. Increased