Answer:
The author's purpose in this excerpt is to teach readers about a code system used during the American Revolution. persuade readers that ciphers are the greatest American invention. argue that Major Tallmadge made a mistake in sharing copies of his codes.
So the question is asking on which of the following choices are the reason why the Indus Valley civilization decline and base on my research, I would say that the answers would be A. The surrounding land was severely deforested , C. Irrigation made the soil salty and unfit for farming and D. <span>Disease reduced the population. I hope this would help </span>
