Consider this animal cell. The organelles in an animal cell are labeled. Part A is a structure with stacked membranes, part E represents small dots on the nucleolus, part F is a network of hollow tubes, flattened sheets, and round sacs, and part G is a bean-shaped structure with folding inside.

Which organelle is responsible for producing the energy for cellular processes?
organelle A
organelle E
organelle F
organelle G