Functions of proteins include

A) providing structural strength in connective tissue.
B) serving as a part of the cholesterol molecule.
C) serving as the primary energy source of cells.
D) transport of nitrogen gas in the blood.
E) padding and insulation.

Proteins

Large, complex molecules made up of amino acids that play many critical roles in the body, including in the structure, function, and regulation of tissues and organs.

Structural Strength

The ability of a material or structure to withstand loads without failing.