Answer
See below for 2 possibilities.
Work Step by Step
First, one could put a bar magnet in the room and see what happens. Does it align with a magnetic field?
Second, one could put a stationary electric charge in the room. A magnetic field exerts no force on a stationary charge. This is stated on page 460. However, in an electric field E, a charge q feels a force of magnitude $q \times E$. A stationary charge will be set into motion.
