Fact 1: Flowing water can slowly dissolve carbon in sedimentary rock.

Fact 2: Rivers are long flowing waters.

Given the two facts above, answer the question "What can slowly dissolve carbon in sedimentary rock?" with the following options: 
- rain
 - rivers
 - sodium
 - oil
 - a solute
 - SO2
 - an ion
 - fens


 

  rivers       