**Core Concept**
Reticulocytes are immature red blood cells that are released into the circulation from the bone marrow. They play a crucial role in the diagnosis and management of various hematological disorders. The correct answer choice will highlight a distinctive feature of reticulocytes that aids in their identification.

**Why the Correct Answer is Right**
Reticulocytes are characterized by the presence of remnants of ribosomal RNA and RNA-rich cytoplasmic inclusions. These inclusions are visible under the microscope using specific stains such as new methylene blue or brilliant cresyl blue. The reticulocyte count is an important parameter in assessing bone marrow function, particularly in cases of anemia or bleeding disorders. The presence of these inclusions is a key feature that distinguishes reticulocytes from mature red blood cells.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not accurately describe a feature of reticulocytes. While reticulocytes do have a larger size compared to mature red blood cells, this is not a distinctive feature that sets them apart.
* **Option B:** This option is incorrect because it refers to a characteristic of mature red blood cells, not reticulocytes. Mature red blood cells do not have a nucleus, whereas reticulocytes retain a small amount of cytoplasmic RNA.
* **Option D:** This option is incorrect because it describes a feature of erythrocyte membrane abnormalities, not a characteristic of reticulocytes. Erythrocyte membrane abnormalities can lead to conditions such as hereditary spherocytosis or elliptocytosis.

**Clinical Pearl / High-Yield Fact**
The reticulocyte count is a useful parameter in assessing bone marrow function, particularly in cases of anemia or bleeding disorders. A high reticulocyte count indicates an increased rate of red blood cell production, while a low reticulocyte count suggests inadequate bone marrow function or red blood cell production.

**Correct Answer: C. Presence of RNA-rich cytoplasmic inclusions.**