Ans.
Respiration involves breakdown of organic molecules, such as glucose in the presence of oxygen to form energy in the form of ATP (adenosine triphosphate).
The mitochondria are known as power house of the cell, where pyruvate (made from glucose) is used to make energy rich ATP molecules in the presence of oxygen, and carbon dioxide is released as byproduct.
Thus, the correct answer is 'option c). mitochondria.'