Final answer:
Baggage on buses must conform to size and weight restrictions as specified by the bus operator, similar to how vehicle and safety regulations apply to service animals on airplanes and weight limits on bridges.
Step-by-step explanation:
When loading or carrying baggage on a bus, the correct answer is that baggage must be limited to a certain size and weight, as specified by the bus operator. Just as there are weight limits for bridges to prevent damage and occupancy limits for rooms to ensure safety, bus operators set baggage restrictions for several reasons. These include ensuring that the baggage doesn't block aisles or exits, fits within designated storage areas like overhead compartments or under-seat spaces, and doesn't exceed weight limitations that could affect vehicle stability and safety. For example, on airplanes, which have similar safety considerations, DOT regulations stipulate that service animals must fit within a passenger's foot space and be harnessed or leashed.