Yellowstone national park was founded in 1872. It covers nearly 3500 mi.² of wilderness and contains many unusual geological features. The park is home to large population of mammals, including bison and elk for years the elk population grew rapidly until they re-introduction of wolves to the park in 1995 which sentence from the comparison describes an interaction.
"The elk population grew rapidly until the re-introduction of wolves to the park in 1995."
The sentence "For years, the elk population grew rapidly until the re-introduction of wolves to the park in 1995" describes an interaction between the elk population and the re-introduction of wolves.
