Mitochondria are also known as the [[1]]  of the cell.

Concept: Mitochondria is a membrane-bound organelle that is found in eukaryotic cells. Mitochondria is cylindrical in shape and it is also known as the powerhouse of the cell. 

Mitochondria are surrounded by two membranes. The outer membrane is smooth and the inner membrane forms various foldings called cristae. Mitochondria contains its own genetic material and it also possesses the ability to self-replicate. Mitochondria is the main site of aerobic respiration in the cell and it is used for the breakdown of carbohydrates and fats. It is also used for the production of ATP which is considered to be the energy currency of the cell.

Hence, the correct answer is a powerhouse.