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

Fact 2: When iron oxidizes it produces iron oxide, more commonly referred to as rust.

Given the two facts above, answer the question "Rust of iron in rocks is a direct result of " with the following options: 
- solar heating
 - high speed fall from space
 - Chemical energy
 - The area was once underwater
 - permineralization
 - Temperature
 - volcanic ejection
 - chemical weathering


 

        chemical weathering 