**Core Concept:** Markers of plasma membrane are substances that are unique or predominantly present on the outer layer of cell membrane, also known as plasma membrane. They provide information about the cell's origin, function, or status.

**Why the Correct Answer is Right:** The correct answer, **Option C: Band 3 protein (SLC4A1)**, is a plasma membrane marker found in red blood cells (RBCs). Band 3 protein is crucial for efficient oxygen transport and maintains the negative charge on the cell membrane of RBCs. It is also involved in the anion exchange process through the membrane, contributing to the cell's unique properties.

**Why Each Wrong Option is Incorrect:**

A. **Option A: Glucose transporter (SLC2A1)** is a transporter protein responsible for facilitating glucose uptake into cells, not specifically a plasma membrane marker.

B. **Option B: Cholesterol** is a component of the lipid bilayer of the plasma membrane, but it is not a unique marker for any specific cell type.

D. **Option D: Cytochrome C** is a protein found in the mitochondria, not the plasma membrane.

**Clinical Pearl / High-Yield Fact:** Plasma membrane markers can be helpful in identifying cell types during diagnostic tests, research studies, or in understanding diseases affecting cell membrane integrity. For example, deficiencies in Band 3 protein can lead to hereditary spherocytosis, a disorder causing hemolysis (destruction of RBCs) due to abnormal membrane properties.

**Correct Answer:** Band 3 protein (SLC4A1) is a plasma membrane marker found on red blood cells (RBCs), making it the correct answer in this question.