Many kinds of air pollution can't be seen, which means A is incorrect. Any kind of pollution can be harmful to you, which means B is incorrect too. Air pollution is very harmful but in most cases can't be directly seen, so C is correct. Pollution can be found everywhere, so D is incorrect also.
If they are both albino there is no chance for them to have any other skin color because it is not in their genes. The phenotype gene is always going to be albino.
