The.correct answer is c. depositional pollution.
Even though there are no industries, and thus pollutants in those regions, they do have a lot of pollution, and it increases every year. This is due to the fact that the pollutants move with the sea currents and with the winds. The sea currents transport the harder and bigger pollutants, while the winds transport the pollutants in gas form and the ones that are tiny particles. So both of these natural phenomenons are transporting pollutants to the poles and make depositions of them.