Thirty years after the forests of the Randall Valley were

Thirty years after the forests of the Randall Valley were destroyed by fire, none of the twelve species of lizards native to the valley remain. Since the absence of trees has increased the average annual temperature in the area by 4 degrees, scientists have hypothesized that the climate change has played a significant role in the disappearance of the lizards.

Structure:
Premise: After 30 yrs 0/12 lizards remain (no one alive)
Premise: Absence of trees ---> increased temperature
Conclusion: Climate change ----> disappearance of lizards

Which of the following, if true, would most strengthen the scientists' hypothesis?

How do we strengthen an argument? We strengthen an argument by showing that the causation is indeed true (that climate change did cause the disappearance of the lizards). How can we show such causation? We show it by providing evidence.

A. Most of the twelve species of lizards native to the Randall valley were already declining in population thirty years ago. This actually WEAKENS the statement. If this were true then the scientists' hypothesis would be wrong.
B. The very same species of lizards can still be found in a neighboring valley, where the destruction of the forests was not accompanied by a rise in temperature. This is what we want. We are trying to show evidence that causation really holds.
C. Scientists believe that even if the region can be replanted it will take many generations before the lizards can be reintroduced into the forests. Out of scope. Yes, this COULD be true but the question still remains, "does this answer choice affect the conclusion?" Ask that and you'll come into terms that it doesn't.
D. Two of the twelve species of lizard have been on the worldwide endangered species list for fifty years.And so? Again, doesn't answer affect the conclusion.
E. The loss of the forests also caused a reduction in the population of snails, slugs and worms, the three main sources of food for the lizards. Like answer choice (A), this WEAKENS the conclusion. Why do we say this? Remember, one of the ways to weaken an argument is to disrupt the causation by introducing another event. For example, the argument says x causes y. One way to weaken the argument is to introduce z and to say that it, not x, causes y.

Hope I helped.