- Absorbing something is a kind of method for taking in something
- Roots are a vehicle for absorbing water and nutrients from soil into the plant
- So, roots are a vehicle for taking in nutrients from the soil

- Roots are a vehicle for taking in nutrients from the soil
- Some minerals are nutrients
- Hence, roots are a vehicle for taking in minerals from the soil

- Roots are a vehicle for taking in minerals from the soil
- Iron is a kind of mineral
- So, roots are a vehicle for taking in iron from the soil

- Roots are a vehicle for taking in iron from the soil
- If something is a vehicle for a process then that something performs that process
- Therefore, roots take in iron from the soil

Therefore, roots take in iron from the soil
Question: Plants need iron to grow. What parts of plants take in iron?
Context: - If something is a vehicle for a process then that something performs that process 
- Iron is a kind of mineral 
- Some minerals are nutrients 
- Absorbing something is a kind of method for taking in something 
- Roots are a vehicle for absorbing water and nutrients from soil into the plant