What must you do in this situation?

Your answer is correct because traffic rules require you to stop in front of the level crossing when a flagman is present holding a stop signal. The flagman is responsible for protecting the crossing and signals when it is unsafe to proceed.

You must not drive past the flagman on either side, as this would disregard their authority and create a dangerous situation with trains or other rail traffic potentially approaching. Stopping in front of the crossing and obeying the flagman ensures your safety and the safety of others.

In summary, always stop when a flagman at a level crossing signals to stop, and wait until you are allowed to proceed. This rule helps prevent accidents with trains at level crossings.