In vertebrate animals, brown fat tissue's color is derived from abundant blood vessels and capillaries. White fat tissue, on the other hand, is specialized for fat storage and contains relatively few blood vessels or capillaries. Brown fat cells have a specialized protein that allows protons to diffuse across the inner mitochondrial membrane. Which of the following might be the function of the brown fat tissue?A) to increase the production of ATPB) to allow other membranes of the cell to perform mitochondrial functionsC) to allow the animals to regulate their metabolic rate when it is especially hotD) to increase the rate of oxidative phosphorylation from its few mitochondriaE) to regulate temperature by converting most of the energy from NADH oxidation to heat

Oxidative phosphorylation happens in the inner mitochondrial membrane, where NADH gives its electrons which are transported in the electron transport chain while protons are pumped from the mitochondrial matrix to the intermembrane space, generating a proton gradient. In most tissues, the protons go back to the matrix via the ATPase, and the gradient energy is used to synthesize ATP.

However, in brown fat there is a protein that allows protons to diffuse across the inner mitochondrial membrane, so the energy generated from the gradient isn't used to produce ATP and it dissipates as heat, increasing body temperature.