I'd say the cricket frogs' population would decrease as mosquitoes' population decreases. Since the number of mosquitoes (which are a more than usual food sources for cricket frogs) is decreasing through out the years. So that'd mean there's less food each year for them and even lesser food the year after that. Let's also add that the same amount of predators hunting them for food is the same each year. If anything that'd further hurt and ensure the decrease of the cricket frogs' numbers rather than help keep their numbers at a constant rate let alone an increasing rate (especially if other variables are not accounted for or presented that could too influence the change of population for the cricket frog, which is true in this case. We are only supplied the information of the cricket frog's prey population rates per year as well as its predators'. Solely from that, we need to infer what change in the population of cricket frogs would be true for this question in this case.)
A and B makes no sense because the predators' population (alligators) aren't increasing or decreasing to begin with according to the graph (instead it is remaining the same number each year). So we can throw that out. D wouldn't be it. If a food source decreases, what depends on said food source probably will as well because that's less food available for them to survive.
