Answer: The correct answer is- Mitochondria.
Mitochondria is known as the power house of the cell as it is responsible for the production of large amount of ATP ( that is the energy currency of cell).
The two stages of cellular respiration takes place inside mitochondria. These stages are- Kreb cycle and electron transport chain. Through electron transport chain ( also called oxydative phosphorylation), large amount of ATP is produced. It is produced when electrons are passed through various protein complexes present in the inner mitochondrial membrane.