- A source of something produces that something
- Cellular respiration is a source of energy for cell activities
- Hence, cellular respiration produces energy for cell activites

- Cellular respiration produces energy for cell activites
- Cellular respiration is when cells extract energy from food to produce energy
- Hence, cellular repiration produces energy by extracting energy from food

- Cellular repiration produces energy by extracting energy from food
- All cells perform cellular respiration
- Therefore, all cells produce energy by extracting energy from food

Therefore, all cells produce energy by extracting energy from food
Q: Which of these is a function of all cells?
Context:
- A source of something produces that something 
- All cells perform cellular respiration 
- Cellular respiration is a source of energy for cell activities 
- Cellular respiration is when cells extract energy from food to produce energy