Final answer:
The correct use of 'rampart' is in option 1, where it describes a defensive wall or structure, commonly used in military contexts for protection.
Step-by-step explanation:
Based on its use in the passage, the most correct use of the word rampart is option 1: The rampart of sand bags protected the town from the flood. The term rampart refers to a defensive wall of a castle or walled city, or any sort of defensive structure. This is evident in the excerpts provided, where ramparts are associated with protection and military defense against floods or enemy forces and are not used as a verb or in a casual purchase context.