The correct answer is A. Mitochondria
The mitochondria is a type of a cell organelle present in eukaryotic cells that produces energy needed for the cell's metabolism. Among others, the mitochondria produce adenosine three phosphate (ATP) which is the most important energy molecule in the cell. Cells that have high energy demands, like for example nerve or muscle cells have a lot of mitochondria. On the other side, adipocytes, the cells that store fat have very few mitochondria.
