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

Fact 2: Oxidation of iron minerals causes the redness of the rocks.

Given the two facts above, answer the question "chemical weathering causes redness of the rocks containing what?" with the following options: 
- iron
 - Urea
 - Gases
 - red stones
 - matter
 - gems
 - coal
 - oranges


 

 iron        