**Core Concept**
Hemosiderin is a protein that accumulates in cells and tissues as a result of iron overload, typically following hemorrhage, hemolysis, or other conditions leading to excessive iron release. The color of hemosiderin is a key characteristic used in histopathological diagnosis.

**Why the Correct Answer is Right**
Hemosiderin has a characteristic yellowish-brown color due to the oxidation of iron within the protein. This coloration is a result of the binding of iron to the protein, which leads to the formation of a stable iron complex. The yellowish-brown color of hemosiderin is a diagnostic feature that distinguishes it from other pigments, such as melanin or lipofuscin.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because hemosiderin does not typically have a greenish color. While some pigments can exhibit greenish hues, hemosiderin's characteristic color is yellowish-brown.
**Option B:** This option is incorrect because hemosiderin does not have a reddish color. While some conditions may lead to the accumulation of hemoglobin, which has a reddish color, hemosiderin is a distinct protein with a different coloration.
**Option C:** This option is incorrect because hemosiderin does not typically have a bluish color. While some pigments can exhibit bluish hues, hemosiderin's characteristic color is yellowish-brown.

**Clinical Pearl / High-Yield Fact**
It's essential to distinguish hemosiderin from other pigments in histopathological diagnosis, as the presence of hemosiderin can indicate conditions such as hemochromatosis, hemosiderosis, or hemorrhage.

**Correct Answer: B. Reddish-brown.