The correct option is
A Iron
Nutrients are compounds in food that provide energy and facilitates growth and repair in the body. It helps to carry out different life processes like development, respiration, etc.
Based on the quantity or amount of nutrients required by the body, they are divided into two categories:
- Macronutrients - Required by the body in large amounts.
- Micronutrients - Required by the body in small amounts.
Macronutrients mainly provide energy for body to carry out different functions and help to build up muscles and tissues. It includes carbohydrates, proteins, and fats.
Micronutrients help to control the different body processes, assist enzymes to catalyse metabolic reactions, helps in neural transmission, synthesis of hormones, etc. They include different minerals (calcium, iron etc.) and vitamins (A, B, C, D, E and K).
Iron is a micronutrient that is essential for haemoglobin production in the body. It's deficiency can lead to anemia (lack enough healthy red blood cells to carry adequate amount of oxygen to body tissues).