Answer:
teach readers about a code system used during the American Revolution.
Explanation:
The lines "He substituted digits for words that would be used in messages. "Long Island," for example, was 728, "arms" was 7, and "city" was 88. There was a number for each month, such as 341 for "January." indicate that the author wants to teach the reader about a code system used during the American Revolution.
Also, the rest of the options don't make any sense whatsoever.
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