The right answer is organelle G, which represents mitochondria.
Mitochondria is the place of cellular respiration. This is a set of reactions that convert glucose into the energy molecule, ATP. This process involves several steps, including the "Krebs Cycle", a set of metabolic reactions that takes place in the mitochondrial matrix. The enzyme that produces ATP is found in the inner membrane of the mitochondria. For these reasons, the mitochondria is often referred to as the cell's energy factory.