Final answer:
The characteristic of proteins that is most accurate is that they are the building blocks of the body. (Option C). They play crucial roles in bodily functions and are not primarily the body's main energy source. Essential amino acids required for protein synthesis must be obtained through diet.
Step-by-step explanation:
Proteins are the building blocks of body tissue, consisting of amino acids. They are crucial for numerous bodily functions including forming muscle fibers, enzymes, and antibodies.
They are also essential nutrients made up of amino acids. While proteins can serve as a fuel source, providing 4 kcal (17 kJ) per gram, they are not considered the body's main energy source.
This role is typically reserved for carbohydrates and lipids, with the latter providing the highest energy density at 9 kcal (37 kJ) per gram.
Proteins are vital for life because they play a significant role in tissue formation, acting as hormones and enzymes, and constitute an integral part of the immune system.
The body can synthesize some amino acids, but others, known as essential amino acids, must be obtained through diet.
Foods such as meat, fish, and legumes are excellent sources of dietary proteins necessary for maintaining healthy bodily functions, including protein synthesis.
Hence, the correct answer is Option C.