You may not park a vehicle carrying hazardous materials within ______ feet of an open fire.

The requirement to not park a vehicle carrying hazardous materials within 300 feet of an open fire is grounded in safety protocols designed to minimize the risk of an explosion or fire caused by the hazardous materials in the vehicle. This distance serves as a buffer zone to protect both the vehicle and the surrounding area from potential hazards associated with flammable or explosive materials.

In the event of a fire, hazardous materials can pose serious threats, including the risk of fire spreading, toxic fumes being released, or even violent reactions occurring. By maintaining this distance, emergency responders have more space to operate safely, and it reduces the risk of ignition sources coming too close to materials that could amplify the fire's impact.

Knowing that the correct answer is 300 feet aligns with training standards and regulatory guidelines for transporting and handling hazardous materials. The distances provided in other options, such as 100, 200, or 400 feet, do not reflect the standard safety guidelines established for hazardous material transport and handling around open flames.