Iron deficiency anemia

Correct answer: C. Iron

Explanation: Iron is required to make haemoglobin, the protein in red blood cells that carries oxygen from the lungs to body tissues. When iron intake, absorption, or stores are inadequate, haemoglobin production may fall and iron-deficiency anaemia can develop, often causing tiredness, weakness, pallor, and reduced concentration. Anaemia can have other causes too, including vitamin deficiencies and blood loss, but iron deficiency is a common nutritional cause. Calcium, fat, and water do not directly form haemoglobin.

Correct answer: C. Iron

Explanation: Iron is required to form haemoglobin, the protein in red blood cells that carries oxygen. Inadequate iron can cause iron-deficiency anaemia, with tiredness, weakness, and reduced work capacity. Iron-rich foods include pulses, meat, eggs, and green leafy vegetables; vitamin C can improve absorption from plant sources. Option C is correct.

Correct answer: A. Formation of hemoglobin

Explanation: Iron is a component of haemoglobin, the red-blood-cell protein that carries oxygen from the lungs to tissues. Inadequate iron can reduce haemoglobin production and contribute to iron-deficiency anaemia, fatigue and reduced work capacity. Calcium absorption, digestion and clotting involve other nutrients and processes. Therefore option A is correct.