Answer: large internal surface area
The mitochondria is the powerhouse of the cell. It is an organelle that produces the chemical energy in the form of ATP during cellular respiration process. As, a part of cellular respiration electron transport chain and chemiosmosis takes place in the mitochondria inner membrane. The cristae are fine tube like structures present at the inner membrane expands the surface area for cellular respiration and enhance the energy production in the form of ATP.