Regarding biological productivity, what do you think is the best explanation for the trend in changing biomass shown in the figure below?

a.) this is best explained by an increase in the number of predators as you move away from the coast. the increase in predators decreases the number of organisms (i. e., biomass) at lower trophic levels.
b.) this is a best explained by a reduction in oxygen as one moves away from the coast. the reduction in oxygen limits aerobic cellular respiration and leads to a decrease in biomass as one moves away from the coast.
c.) this is best explained by a reduction in the availability of food as one moves away from the coast. input of nutrients (from runoff and less commonly upwelling) fuels primary production, thus allowing a greater number of producers and energy availability for higher trophic levels.
d.) this is best explained by the great pressure at depth as one moves away from the coast. this pressure makes it harder for organisms to survive and thus reduces biomass away from the coast.