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: 
- an ion
 - rivers
 - a solute
 - rain
 - oil
 - sodium
 - fens
 - SO2


 

  rivers       