Final answer:
b. Proteins are the essential nutrients that serve as the basic framework for muscles, bones, and blood, critical for growth, repair, and function of various body systems.
Step-by-step explanation:
The type of essential nutrient that serves as the basic framework for muscles, bones, and blood is proteins. Proteins are critical for the growth and repair of body tissues and play a key role in the structure and function of all living cells. Unlike carbohydrates and fats, which are primarily used for energy, proteins contribute to the structural components of the body, including muscles, bones, skin, and blood. They are essential for the formation of enzymes, hormones, and other substances the body uses to regulate and maintain homeostasis.
The body also uses proteins to produce antibodies which are necessary for immune defense mechanisms. Compared to carbohydrates, which compose only 2% of your body weight and are used mostly for energy, proteins are a more dominant component in the human body's structure. Essential nutrients such as vitamins A and K are also important; vitamin A helps maintain connective tissue, while vitamin K is crucial for blood clotting. However, they are not the primary framework for muscular and skeletal systems as proteins are.