You are presented with the question "What gives a rusty red color to sedimentary rocks?" and the following answer choices: 
- food coloring
 - The area was once underwater
 - chemical weathering
 - remains of prehistoric life
 - deoxyribonucleic acid
 - sea urchins
 - dirt
 - earthquakes

Now knowing that chemical weathering causes iron in rock to oxidize and iron oxide gives a rusty red color to sedimentary rocks, choose the best answer.


 

   chemical weathering      