i took this class the answer is medulla because investigators may look for the presence or absence of a medulla, which is a set of cells that runs through a hair. The medulla is typically different depending on which species the hair came from. This is one way to distinguish between animal and human hair.
Cellular respiration takes place in mitochondria of a cell, hence it is also known as power house of cell , because it gives us energy in the form of ATP molecule .