Final answer:
B. the Missouri-Kansas-Texas Railroad.
The Missouri-Kansas-Texas Railroad is the line that meets the described characteristics, being built along Cherokee tribal lands, between 1870 and 1872, as a north-south line through Vinita and Fort Gibson.
Step-by-step explanation:
The correct answer to the question regarding the characteristics of a specific rail line built in the Indian Territory between 1870 and 1872 that was built along the border of Cherokee tribal lands, was a north-south line, and traveled through Vinita and Fort Gibson is B. the Missouri-Kansas-Texas Railroad. This line, commonly referred to as the MKT or the Katy, was one of the railroads built following the era of the First Transcontinental Railroad. It was constructed during the time period specified and fit the geographical descriptions provided in the question. This contrasts with other railroads such as the Atlantic and Pacific Railway, the Atchison, Topeka, and Santa Fe Railroad, and the Chicago, Rock Island, and Pacific Railroad, that were also part of the development of railroads after the completion of the First Transcontinental Railroad, but did not meet all the specified characteristics.