Fact 1: Carbon may be stored in sedimentary rock for millions of years.

Fact 2: Limestone is a type of sedimentary rock.

Given the two facts above, answer the question "what can carbon be stored in for millions of years?" with the following options: 
- limestone
 - fossil fuels
 - hydrocarbons
 - graptolites
 - fish
 - humans
 - h2o
 - layers of fat


 

 limestone        