What needs to be considered when shipping animals of varying sizes?

When shipping animals of varying sizes, the most important consideration is that different sizes should not be shipped in the same container. This is crucial because animals of different sizes may have differing needs related to space, temperature, and comfort, which can greatly affect their welfare during transport. Mixing animals of various sizes can lead to stress and injury, as larger animals might unintentionally harm smaller ones in a confined space. Additionally, animal behavior can be unpredictable, and the presence of an incompatible size can lead to aggression or anxiety.

The other choices lack a proper understanding of the complexities involved in animal shipping. Mixing different sizes, even in small numbers, can still pose risks to the animals' safety and well-being. Focusing solely on size while disregarding age overlooks the fact that age can also influence an animal's behavior and response to stress. Lastly, prioritizing the shipping order based on size without considering the needs and comfort of the animals could compromise their welfare. Thus, it is essential to have separate containers suited to each specific size to ensure safe and humane transport.