Some forested areas of the country have large, flat-topped boulders left behind by glaciers. The tops of the boulders have become covered with lichens, grasses, shrubs, and even some small trees. Deer can jump onto the top of shorter boulders to graze; however, none of the deer can jump onto the tallest boulders. Scientists sampled vegetation from the tops of these boulders, some of which were grazed by deer and some of which were not. Scientists observed that the most diverse plant growth occurred on the boulders that could not be reached by deer.

Question

(g) Identify the control group for the investigation.