In Metzgar's Experiments on Learning in White-Footed Mice,the Sticks

In Metzgar's experiments on learning in white-footed mice,the sticks

A) functioned as obstacles for the mice.
B) could be used by the mice to help them hide from the predator.
C) could be used by the mice as tools for capturing prey.
D) served as distance markers for recording how far the mice had moved.
E) prevented the mice from escaping.