Final answer:
The mitochondrion is known as the powerhouse of the cell and is responsible for the production of ATP through the process of cellular respiration.
Step-by-step explanation:
The cellular organelle responsible for producing energy in the form of ATP when both glucose and oxygen are available to the cell is the mitochondrion. These organelles are known as the "powerhouses" or "energy factories" of a cell. The process that takes place in mitochondria is called cellular respiration, where chemical energy from nutrients like glucose is transformed into ATP, with oxygen being utilized and carbon dioxide released as a byproduct. In eukaryotic cells that require a lot of energy, such as muscle cells, there is a high concentration of mitochondria to meet this demand. Hence, the correct answer is C) Mitochondrion.