What is the primary function of mitochondria?

The correct option is Energy production.

Step-by-Step Explanation:

1. Understanding Mitochondria:
Mitochondria are membrane-bound organelles found in the cytoplasm of eukaryotic cells. They are commonly known as the "powerhouses of the cell."

2. Primary Function (Energy Production):
The main role of mitochondria is cellular respiration, a biochemical process where nutrients (such as glucose) are broken down in the presence of oxygen to generate adenosine triphosphate (ATP). ATP serves as the main chemical energy currency used by cells to perform essential biological processes.

3. Evaluating Other Options:
- Protein synthesis: This is primarily performed by ribosomes and the rough endoplasmic reticulum.
- Cell division: Centrosomes and centrioles play key roles in organizing cell division.
- Waste removal: Lysosomes are mainly responsible for digesting and removing cellular waste.

Therefore, the primary function of mitochondria is Energy production.