When co2 dissolves in water it chemically combines with water to form

The carbon dioxide reacts with water to form carbonic acid.

Explanation:

      CO2+H2O=H2CO3

In this reaction carbon dioxide(CO2) and water(H2O) act as reactant  to form carbonic acid(H2CO3) which is a weak acid.

       The above reaction is an important reaction carried out by  bicarbonate buffer system to maintain normal acid base balance inside our body but this buffer system includes an additional reaction in with carbonic acid is ionized to form H+ and HCO3- ion or bicarbonate ion.

oceans

indian ocean

pacific ocean

atlantic ocean

arctic ocean

southern ocean

i believe it would cause an increase of percipitation, though i could be wrong. so i would say b is the answer.