What type of dietary nutrient is crucial for muscle development and maintenance?

Proteins are essential for muscle development and maintenance due to their role as building blocks for body tissues, including muscle. They are made up of amino acids, which are needed for the growth, repair, and maintenance of muscle fibers. When muscles are subjected to stress, such as during exercise, they need proteins to recover and adapt, which ultimately leads to increases in muscle mass and strength.

While carbohydrates are important for providing energy during workouts and fats serve various roles, including energy storage and hormone production, they do not have the same direct role in muscle repair and synthesis as proteins do. Vitamins, while vital for overall health and aiding in many biochemical processes, are not directly involved in muscle building or maintenance. Therefore, the critical nature of proteins in supporting and enhancing muscle development is what makes it the correct answer.