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.
Input: Question: How many years did the war last that Eden's great-grandfather commanded the 2nd regiment of foot? Passage:Eden's great-grandfather was William Iremonger, who commanded the 2nd Regiment of Foot during the Peninsular War and fought under Wellington (as he became) at Vimeiro. He was also descended from Governor Sir Robert Eden, 1st Baronet, of Maryland and, through the Calvert Family of Maryland, he was connected to the ancient Roman Catholic aristocracy of the Arundell and Howard families, some of whom were Roman Catholics like the Dukes of Norfolk and others Anglican such as the earls of Carlisle, Effingham and Suffolk. The Calverts had converted to the Established Church early in the 18th century to regain the proprietorship of Maryland. He was also descendant from the Schaffalitzky de Muckadell family of Denmark, and Bie family of Norway. Eden was once amused to learn that one of his ancestors had, like Churchill's ancestor the Duke of Marlborough, been the lover of Barbara Castlemaine.
Links: a. Peninsular War b. Peninsular War c. Denmark d. Arthur Wellesley, 1st Duke of Wellington
Output:
a