Final answer:
The only situation where it is allowed to operate an ambulance with flashing red lights and sirens is when responding to an emergency or transporting a patient.
Step-by-step explanation:
When operating an ambulance, you are permitted to use flashing red lights and sirens in specific scenarios that are determined by laws and regulations. The correct answer to when you can use these emergency signals is: a. When you are responding to an emergency call or transporting a patient. Ambulance drivers use these signals to navigate through traffic quickly and safely to provide urgent medical help or to get to the hospital as fast as possible. It is not permissible to use these signals for personal convenience or non-emergency situations, such as getting to Tim Horton's quickly for a break or simply because there is a lot of traffic.
GRASP CHECK
If you are standing on the sidewalk facing the street and an ambulance drives by with its siren blaring, the frequency that you observe will most closely match the actual frequency of the siren when it is directly in front of you.