Respiratory system.
Oversimplified Explanation: they enter the lungs, which is part of the respiratory system.
Answer:
Explanation:
1. cools quickly on the earth's surface
Extrusive igneous rock
2. cools slowly beneath the earth's surface
Intrusive igneous rock
3. formed from the remains of living organisms
Organic sedimentary rocks
4. formed from pieces of other rocks cemented together
Clastic sedimentary rock
5. formed when dissolved minerals harden
Chemical sedimentary rock
6. formed from heat and pressure
Metamorphic rocks