**Core Concept**
Osmotic fragility is a property of erythrocytes (red blood cells) that refers to their susceptibility to hemolysis (rupture) in hypotonic solutions. The osmotic fragility of erythrocytes is determined by the balance between the strength of the cell membrane and the osmotic pressure of the surrounding environment.

**Why the Correct Answer is Right**
Red blood cells with increased osmotic fragility are more prone to hemolysis in hypotonic solutions due to a weakened cell membrane. This is typically seen in cells with a deficient or defective cell membrane, such as in hereditary spherocytosis. In this condition, the abnormal spectrin-actin cytoskeleton leads to a loss of cell membrane surface area, resulting in increased osmotic fragility.

**Why Each Wrong Option is Incorrect**
* **Option A:** This choice is incorrect because increased osmotic fragility is not typically associated with anemia of chronic disease, where the primary issue is impaired erythropoiesis rather than a defect in the erythrocyte membrane.
* **Option B:** This choice is incorrect because polycythemia vera is characterized by an increase in red blood cell mass, but not necessarily an increase in osmotic fragility.
* **Option C:** This choice is incorrect because beta-thalassemia major is characterized by a severe reduction in beta-globin chains, leading to ineffective erythropoiesis and anemia, but not necessarily an increase in osmotic fragility.

**Clinical Pearl / High-Yield Fact**
Hereditary spherocytosis is an inherited disorder characterized by the production of abnormal, sphere-shaped erythrocytes with increased osmotic fragility. This condition often presents with jaundice, anemia, and splenomegaly.

**Correct Answer:** D. Hereditary spherocytosis.