What is the primary reason a passenger must use a carrier for their animal on the bus?

The primary reason a passenger must use a carrier for their animal on the bus is to ensure the safety of all passengers. When animals are transported in a secure carrier, it helps prevent them from becoming a distraction or causing any unforeseen incidents during the bus ride, which could potentially affect the safety and comfort of fellow passengers. Using a carrier also helps contain the animal, reducing the risk of escape, injury, or aggressive behavior towards other passengers or staff. This focus on safety is essential in public transportation settings where the well-being of all individuals is a top priority.