Answer:
The answer is letter "A". Fort Gibson when it was built was the US military fort that was the farthest West.
Explanation:
Fort Gibson is known as a historic place with military importance in Muskogee County, Oklahoma. It was built with the objective of safeguarding the US border in the Indian territory from 1824 to 1888.
When it was built, it was the site that was the farthest West than any other military post in the United States with the objective of maintaining peace on the western border. Another goal that was sought with the construction of this fort was to protect the southwestern border of Louisiana Purchase.
This work was in charge of Colonel Matthew Arbuckle. He commanded the United States Infantry from Fort Smith, Arkansas and moved his troops to establish the Gibson cantonment. The date on which this action took place was April 21, 1824 in the Grand River (Oklahoma), near the place where the waters of this river meet the Arkansas River.
