Final answer:
Muscles (D) from meat, poultry, and fish are a source of protein that contributes to the structure and function of various body tissues, including muscles, hair, and nails. Proteins are composed of amino acids and fall into the category of complete or incomplete based on their amino acid content.
Step-by-step explanation:
The source of protein found in meat, poultry, fish that contributes to muscle, hair, nails, and cell membrane structure is muscles (D). These proteins provide essential amino acids and are critical for the maintenance and repair of tissues in the human body.
Proteins are organic compounds composed of amino acids, which are necessary for the synthesis of new proteins in the body. These proteins serve various functions, including the formation of muscle tissue, production of enzymes, and support of immune system functions. In addition to meat and fish, proteins can also be obtained from plant sources such as quinoa and soy, but animal sources provide complete proteins with all nine essential amino acids.
It's important to include a variety of protein foods in your diet to improve nutrient intake and health benefits. Foods like nuts, seeds, beans, legumes, poultry, and seafood can offer a rich array of proteins. For adults, it is recommended to consume two 4-ounce servings of seafood per week and choose lean cuts of meat.