Which macronutrient is essential for building and repairing tissues?

The selected answer is correct because protein is a critical macronutrient that plays a fundamental role in building and repairing tissues in the body. Proteins are made up of amino acids, which are the building blocks necessary for the formation of new tissues and the repair of damaged ones. This is particularly important for muscle tissue, skin, hair, and even the body's internal organs.

Additionally, proteins are involved in numerous biological processes, including the production of enzymes and hormones that regulate various functions within our bodily systems. When the body is injured or after strenuous exercise, protein intake becomes especially vital as it supports recovery and helps the body to heal.

While carbohydrates and fats provide energy and support various bodily functions, they are not primarily responsible for tissue repair and growth like proteins are. Vitamins, while essential for many metabolic processes, do not function as the building blocks for tissues. Hence, protein stands out as the macronutrient specifically crucial for tissue construction and repair.