**Core Concept**
Hereditary spherocytosis is a genetic disorder characterized by the production of abnormal, sphere-shaped red blood cells (RBCs) due to mutations in genes encoding proteins of the RBC membrane. These mutations lead to a decrease in membrane surface area, resulting in a reduced mean corpuscular volume (MCV) and a variable degree of hemolysis.

**Why the Correct Answer is Right**
The correct answer, **Reduced MCHC**, is incorrect because hereditary spherocytosis is typically associated with an increased mean corpuscular hemoglobin concentration (MCHC). This is due to the fact that the same amount of hemoglobin is packed into a smaller, more compact cell volume. A reduced MCHC would be more characteristic of conditions with a decreased hemoglobin content, such as anemia of chronic disease or iron deficiency anemia.

**Why Each Wrong Option is Incorrect**
**Option B:** Normocytic anemia is incorrect because hereditary spherocytosis typically presents with microcytic anemia, characterized by a reduced MCV. The presence of spherocytes leads to a shortened RBC lifespan, resulting in a decrease in MCV.

**Option C:** Positive pink test is incorrect because the pink test, also known as the osmotic fragility test, is actually used to diagnose hereditary spherocytosis. Red blood cells in this condition are more susceptible to hemolysis in hypotonic solutions, resulting in a positive pink test.

**Option D:** Normal WBC count is incorrect because hereditary spherocytosis can be associated with an increased risk of infections, which may lead to an elevated white blood cell (WBC) count. However, a normal WBC count does not exclude the diagnosis.

**Clinical Pearl / High-Yield Fact**
A key feature of hereditary spherocytosis is the presence of spherocytes in the peripheral blood smear, which can be confirmed by a positive pink test. This is a classic example of a laboratory feature that can aid in the diagnosis of this condition.

**✓ Correct Answer: A. Reduced MCHC**