**Core Concept**
Iron deficiency anemia is a condition characterized by a decrease in the production of hemoglobin due to insufficient iron availability. This leads to a reduction in the number of red blood cells and their ability to carry oxygen to tissues.

**Why the Correct Answer is Right**
Iron deficiency anemia is typically associated with decreased serum iron levels, decreased total iron-binding capacity (TIBC), and a low transferrin saturation index. However, in some cases, particularly in iron deficiency anemia of chronic disease, TIBC may be elevated due to increased production of acute-phase proteins. This increase in TIBC can lead to a paradoxical increase in serum iron levels, despite a low iron stores.

**Why Each Wrong Option is Incorrect**
**Option A:** Elevated TIBC is often seen in iron deficiency anemia, especially in the context of chronic disease, so this option is incorrect.
**Option B:** Decreased serum iron levels are a hallmark of iron deficiency anemia, making this option incorrect.
**Option C:** Low transferrin saturation index is a characteristic feature of iron deficiency anemia, so this option is incorrect.

**Clinical Pearl / High-Yield Fact**
In iron deficiency anemia, it's essential to consider the underlying cause, as it may be related to chronic disease, pregnancy, or menstrual blood loss. A thorough medical history and laboratory evaluation are crucial in diagnosing and managing iron deficiency anemia.

**Correct Answer: C. Low transferrin saturation index is a characteristic feature of iron deficiency anemia.**