Flowing water can slowly dissolve carbon in sedimentary rock, and water falls from the sky and flows downhill due to the force of gravity. Given these facts, what moving downhill due to the force of gravity can dissolve carbon in sedimentary rock among the following options:
- river
 - Raft
 - pebbles
 - rain
 - water
 - sand
 - oxygen
 - craters


 

     water    