**Core Concept**
Iron absorption is a crucial process that allows the body to obtain essential iron for various physiological functions. The majority of iron absorption occurs in the duodenum and jejunum, the first two parts of the small intestine, where specific mechanisms facilitate the uptake of dietary iron.

**Why the Correct Answer is Right**
Iron is most commonly absorbed from the duodenum, primarily due to the presence of specific transport mechanisms, such as the divalent metal transporter 1 (DMT1). This transporter is responsible for the uptake of non-heme iron, which is the most common form of dietary iron. The acidic environment of the duodenum, created by the secretion of gastric acid, helps to convert non-heme iron into a more soluble and bioavailable form.

**Why Each Wrong Option is Incorrect**
**Option A:** The stomach is the primary site of iron storage, with ferritin and hemosiderin storing excess iron. However, it is not the primary site of iron absorption.
**Option B:** The ileum is the primary site of vitamin B12 absorption, but it plays a minor role in iron absorption.
**Option C:** The colon is involved in water and electrolyte absorption, but it is not a primary site of iron absorption.

**Clinical Pearl / High-Yield Fact**
The acidic environment of the duodenum is crucial for iron absorption, as it converts non-heme iron into a more soluble and bioavailable form. This is why patients with achlorhydria, a condition characterized by a lack of gastric acid, often require iron supplements to prevent iron deficiency anemia.

**Correct Answer:** C.