Scientists studying climate change have found that global warming not only increases the temperature of the planet but also leads, on average, to an earlier arrival of the spring season and a later arrival of the autumn season. Though some argue that this effect on the seasons is advantageous because it increases the length of the summer growing season, leaders of the World Wildlife Fund fear that many animal species will not be able to adapt to the altered season lengths and will thus soon face extinction.

Which of the following, if true, provides the best evidence in support of the view held by the leaders of the World Wildlife Fund?

View of leaders of WWF: Many species would not be able to adapt to the changing length of seasons and will face extinctions.

(A) When spring arrives earlier than usual, most species of hibernating mammals are forced to emerge from hibernation earlier than usual and to find alternative food sources to supplement their regular diets. -- But they may be able to adapt. This choice leaves with some ambiguity. Keep but this will be eliminated later.

(B) As the planet's temperature rises, the average global sea surface temperature also rises, endangering several marine organisms that reside near the sea surface and that can only survive within very narrow temperature windows. -- Here the endangering is occuring due to changing temperatures and not changing seasons. Eliminate.

(C) Many species of salmon rely on seasonal changes in temperature to signal the start of their annual migrations and will leave their freshwater birthplaces early if spring arrives early; as a result, the populations of several types of freshwater insects consumed by those species of salmon will grow exponentially, infesting thousands of acres of crops on which humans rely. -- This is endangering human beings and is not pointing to the fact that salmons, if they migrate early, will be in any kind of danger. And we want to strengthen the argument of animal specie being endangered due to changing length of seasons. Eliminate.

(D) The young of many species of birds and rodents feed exclusively on caterpillars, whose metamorphosis into butterflies is triggered by seasonal changes in temperature. -- Correct choice. This sticks to what is asked by the question stem. Changing length of season will reduce the food (caterpillars) of many species of birds since caterpillars i.e. the food will metamorphosize into butterflies. And ofcourse this will endanger the specie.

(E) As the length of the summer growing season increases, the amount of carbon emissions produced by humans gradually increases, exacerbating the increase in global temperatures that will likely endanger hundreds of animal species. -- Close choice. But imo this choice is still dependent on human activity. Changing length of seasons DOES NOT cause the endangerment of species. If human activity can be curtailed, the WWF argument would not stand. Eliminate. We need direct causation and effect.

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