What hypothesis is best supported by a graph illustrating an increase in the food supply of cardinals?

The hypothesis that the cardinals' food supply increased is well-supported by the graph illustrating an increase in food supply for these birds. An increase in the food supply provides more resources for the cardinals, which can lead to a variety of positive effects on their population, such as improved survival rates, better reproduction, and increased population growth. When food is more abundant, cardinals can more easily find sufficient nourishment, which is crucial for their health and reproductive success. This correlation between food availability and the well-being of an organism is a fundamental concept in ecology, highlighting how vital resources like food influence animal populations directly.

Other hypotheses, such as cardinals dispersing over a larger area or migrating to a different habitat, do not directly address the impact of increased food supply, which is the focal point of the question. Similarly, the idea that no significant changes occurred contradicts the concept of how food supply influences population dynamics. Therefore, the best hypothesis supported by the given graph is indeed that the cardinals' food supply increased.