input question: What is the final step of the following process: - Particles in the environment interact with rocks - The particles remove small pieces of the rock each time they touch the rocks - The particles continue to hit, brush against, or grow against the rocks - The rock eventually is broken apart by this contact - The pieces of the rock are now small rocks???
output answer: The rock pieces are worn away into smaller and smaller pieces by the same forces

What is the final step of the following process: - Contact is made with a virus - The virus enters the human or animal body - The virus goes to the part of the body that contains its food - The virus consumes part of the body or materials that the body uses - The virus replicates and spreads
----
Answer: The virus causes symptoms in the body as the immune system tries to expel the virus.

Q: What is the final step of the following process: - Warm weather causes water to evaporate - The water rises up in the air - It starts to cools down - The water starts to condense - It forms into clouds
A: When there is enough moisture in the clouds it starts to rain.

Question: What is the final step of the following process: - The earth develops cracks deep beneath the surface - The cracks get very long and big in some places - The earth places pressure against the rocks on both sides of the cracks - The pressure causes the rocks to press against each other very hard - The cracks continue to develop - The earth moves against itself on both sides of the cracks - The pressure and movement around the cracks causes the rocks to crumble in some places - A lot of energy is released - The energy causes seismic waves
Answer: The seismic waves move the earth in an earthquake.

[Q]: What is the final step of the following process: - Blood is sent to the liver - The liver uses chemicals and proteins to treat the blood - The blood is cleaned - Energy is produced
****
[A]: The blood leaves the liver cleaned.

Problem: Given the question: What is the final step of the following process: - Water comes into contact with something made of iron - The water combines with carbon dioxide in the air to form carbonic acid - As the acid is formed, the iron starts to dissolve - Some of the water breaks down into hydrogen and oxygen - The free oxygen and dissolved iron bond together
++++++++++++++++++++++++++++++++
The answer is:
They form iron oxide, which is rust