Answer:
That winter, adults, and children ate little, but the animals ate least of all.
Step-by-step explanation:
When the adverbs are formed by joining '-ly' to the adjective, they are known as irregular adverbs. All adverb does not follow the same rule. For example, fast become fastly.
Some of the adverbs do not follow the normal rule. For example, good becomes well, fast remains fast.
In the above sentence, the irregular adverb that should be used most appropriately is 'least'.