**Core Concept**
Total Iron Binding Capacity (TIBC) is a measure of all proteins available for binding mobile iron, including transferrin. An increase in TIBC indicates an increase in the amount of transferrin available for iron binding, often seen in iron deficiency states.

**Why the Correct Answer is Right**
In iron deficiency anemia, the body attempts to compensate for the lack of iron by increasing the production of transferrin, a protein responsible for binding and transporting iron. This results in an increase in the total iron-binding capacity (TIBC) as more transferrin becomes available to bind iron. This is a compensatory mechanism to capture any available iron, making it a hallmark of iron deficiency.

**Why Each Wrong Option is Incorrect**
* **Option A:** In hemochromatosis, iron overload occurs due to excessive absorption of iron. This leads to a decrease in TIBC, not an increase.
* **Option B:** In anemia of chronic disease, there is a decrease in TIBC due to inflammation and the production of hepcidin, which decreases iron absorption and availability.
* **Option C:** In thalassemia major, there is a significant reduction in red blood cell production, but TIBC is not typically increased. Instead, there may be a compensatory increase in erythropoietin production.

**Clinical Pearl / High-Yield Fact**
Iron deficiency anemia is the most common cause of anemia worldwide, affecting approximately 1.6 billion people, making it essential to recognize the increase in TIBC as a diagnostic clue in iron deficiency states.

**Correct Answer: A. Iron deficiency anemia**