6. Cells produce energy from (a) muscles. (b) oxygen and food. (c) carbon dioxide.

Cells produce energy primarily from oxygen and food, specifically through a process called cellular respiration. In this process, cells break down glucose—a type of sugar derived from food—using oxygen to release energy in the form of ATP (adenosine triphosphate), which powers various cellular activities. So next time you enjoy a meal, remember that your cells are busy turning that food into energy for all your daily adventures! Mitochondria, often referred to as the "powerhouses" of the cell, play a crucial role in energy production. They are like tiny energy factories where the conversion of nutrients into ATP occurs. If you think of your body as a car, mitochondria are the engine that keeps it running smoothly, ensuring you have the energy to sprint, dance, or even just solve that last puzzle you’ve been working on!