Final answer:
An increase in food supply led to an increase in the clawcat population size.
Step-by-step explanation:
The change that led to the increase in the clawcat population size was an increase in their food supply. For example, if there was an increase in the number of rodents in the area, which are the prey of clawcats, then more clawcats would have access to food and their population would increase.
This change led to an increase in the clawcat population size because more available food meant that more clawcats could survive and reproduce. As a result, there would be more offspring and the population would grow.