A species of fish has red and white colors. Over time, white fish become more common in the population. Which statement explains why this may have happened?

well, that's easy; the answer's c, "it reduces contamination of the water and substrate of the estuary."

volcanoes (an event in the geosphere) release a large amount of particulate matter into the atmosphere. these particles serve as nuclei for the formation of water droplets (hydrosphere). rainfall (hydrosphere) often increases following an eruption, stimulating plant growth (biosphere).

sex cells are usually half's then they find another half and make a fertilize egg

multiple allele inheritance is traits controlled by more than 2 alleles (ex: pigeons having 3 alleles of one gene govern their feather color).   so the answer is a.