Final answer:
Vehicles transporting passengers for hire typically need to have a Dry powder extinguisher onboard, as it is effective on multiple fire types. The correct option is 4.
Step-by-step explanation:
The type of fire extinguisher required for vehicles transporting passengers for hire is generally a Dry powder extinguisher. This kind of extinguisher is versatile and effective on various types of fires, including Class A (combustibles), Class B (flammable liquids), and Class C (electrical equipment) fires, which makes it suitable for the diverse potential fire sources in a vehicle environment.
It's crucial to note that the specific requirements may vary based on local regulations and transport standards, so it is always best to consult with the appropriate regulatory body for the most accurate information. Hence, 4 is the correct option.