Fact 1: Chemical weathering causes iron in rock to oxidize.

Fact 2: Asteroids are typically made of rock or iron.

Given the two facts above, answer the question "What causes iron in asteroids to oxidize?" with the following options: 
- aliens
 - chemical weathering
 - flow of electrons
 - hydrogen and oxygen
 - water
 - Chemical energy
 - fossil fuels
 - ice


 

  chemical weathering       