Franz and Eleonore Sauer Demonstrated That, When Placed Inside a Planetarium

Multiple Choice

Franz and Eleonore Sauer demonstrated that, when placed inside a planetarium so that the nighttime sky could be controlled, sylviid warblers oriented themselves in the proper migratory direction for that time of year by taking their bearings from the

A) moon.
B) planets.
C) stars.
D) sun.