Final answer:
The number of organelles, enzymes, and mitochondria in a cell can vary, depending on the cell's function and energy needs.
Step-by-step explanation:
Cells contain organelles, such as mitochondria, which are responsible for producing energy within the cell. The number of mitochondria in a cell depends on the cell's energy needs. For example, active muscles cells may have thousands of mitochondria, while less active cells like red blood cells do not have any. Therefore, the correct answer is d) all of the above.