Detailed Instructions: In this task, you're given a question, a context passage, and four options which are terms from the passage. After reading a passage, you will get a brief understanding of the terms. Your job is to determine by searching and reading further information of which term you can answer the question. Indicate your choice as 'a', 'b', 'c', or 'd'. If you think more than one option is plausible, choose the more probable option to help you answer the question.
Problem:Question: How long had Libby Prison been in existence for by the year Wessells was promoted to major of the 6th US Infantry? Passage:On June 6, 1861, he was promoted major of the 6th US Infantry, and on Aug. 22 of that year he received the colonelcy of the 8th Kansas Infantry. After serving on the Missouri border he resumed his commission in the regular army Feb. 15, 1862, and in March was transferred to the Army of the Potomac. He was made a brigadier-general of volunteers April 25 and served in the Peninsula, receiving the regular army brevet of lieutenant- colonel for gallantry at the Battle of Fair Oaks, where he was wounded. In Gen. George B. McClellan's change of base he commanded the rear-guard, and then engaged in the defense of Suffolk, Va., afterward serving in North Carolina. After serving at Kinston, Goldsboro, and New Berne, he was placed over the sub-district of the Albemarle, taking command May 3, 1863. On April 17, 1864, he was attacked at Plymouth, North Carolina, where he had a garrison of about 3,000 men, by Gen. Robert F. Hoke with about 15,000 Confederate troops and the iron-clad CSS Albemarle After a gallant defense which lasted three days Gen. Wessells surrendered the town. He was taken to Libby Prison, whence he was transferred successively to Danville, Macon and Charleston. At the last-named place he was one of the officers that were placed under the fire of the Union batteries on Morris island. On Aug. 3, 1864, he was exchanged, and on Nov. 11 he became commissary of prisoners, which post he held until the close of the war. He was also placed in charge of a conscription center in New York. He was promoted lieutenant-colonel Feb. 16, 1865, and brevetted colonel to date from April 20, 1864, "for gallant and meritorious services during the rebel attack on Plymouth, N. C." On March 13 he was given the regular army brevet of brigadier general.
 Links: a. CSS Albemarle b. Battle of Seven Pines c. Libby Prison d. CSS Albemarle
Solution:
c