If the Chesapeake population overfished anchovy and herring, both populations would be affected and the total number of organisms in each of them would decrease, because many of them would die as prey.
As the Food Web shows, anchovy and herring both feed on krills (because the arrow always points towards the predator). Therefore, the population of krill will lack two predators, and the krills that shoul be dying as prey for anchovy and herring would survive, causing an increase in the krill population.
On the other hand, the Food Web shows that both herring and anchovy are preys for gulls. In that case, the gulls would have less food, because its preys (anchovy and herring) would not beas available as they need too. This would cause gulls to fight for food and to die of starvation, causing a decrease in gulls population, that would be suffering.
Therefore, the correct answer is d. The gull population would suffer, while the krill population would grow.