A police officer stationed along the route of a parade has been ordered not to allow cars to cross the route while the parade is in progress. An ambulance driver on an emergency run attempts to drive an ambulance across the route while the parade is passing. Under these circumstances, the officer should

• Ask the driver to wait while the officer calls headquarters and obtains a decision.
• Stop the parade long enough to permit the ambulance to cross the street.
• Direct the ambulance driver to the shortest detour available, which will add at least ten minutes to the run.
• Hold up the ambulance in accordance with the order.