When animals are being used to pull loads, these animals are commonly referred to as __________ animals.

When animals are utilized for the purpose of pulling loads, they are referred to as "draft animals." This terminology specifically describes animals that are physically capable of exerting the required strength and endurance needed for such tasks. Draft animals, including breeds like horses, oxen, and mules, are bred and trained for their ability to work in this capacity, making them essential in agricultural settings, transportation, and various labor-intensive industries.

The other terms, while they may describe attributes related to strength or physical capability, do not accurately capture the specific role these animals play in load-bearing tasks. For example, "strong" generally describes the inherent physical power of an animal but lacks the specificity of their function in loading tasks. "Haul" refers to the action of pulling itself rather than the type of animal that performs that action. "Sturdy" can describe an animal's overall build and resilience but does not convey the purpose of load-pulling. "Draft" properly aligns with both the functional and the historical context of animals used in this way.