The white clover is a plant that is native to Europe and Asia. It was introduced in North America around 300 years ago. Some white clover plants produce cyanide and others do not. Cyanide is poisonous to herbivores that eat the white clover, such as snails, slugs, and voles. The circle graphs show the distribution of white clover plants producing cyanide in Minnesota and North Carolina, in the United States.

a. Compare the distribution of the two kinds of white clover in Minnesota and North Carolina.