The population size of mountain pine beetles in the American Northwest has long been held in check by freezing temperatures during the winters. As winters warm, populations of pine beetles are increasing, killing whitebark pine forest. Grizzly bears rely on the nuts of whitebark pine trees. Do you think climate change is affecting the fitness of the grizzly bear population? a. No, because climate change is not a problem yet. b. No, because climate change is affecting the beetles, not the bears. c. Yes, because climate change is decreasing the food supply of the bears, which means they will be less strong. d. Yes, because climate change is decreasing the food supply of the bears, which is likely to reduce their ability to survive or reproduce.