Final answer:
The structure of the sentence “Presently, the lion stumbled and gave a low moan” is chronological order.
Step-by-step explanation:
The structure of the sentence “Presently, the lion stumbled and gave a low moan” is chronological order. In this structure, events are presented in the order in which they happen. In this sentence, the lion first stumbles and then gives a low moan. The use of the word “presently” indicates a temporal progression, further supporting the idea of chronological order.