Given the task definition, example input & output, solve the new input case.
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.
Example: Question: When did the operation during which the 704th dropped supplies to allied troops near Nijmegen begin? Passage: The group was occasionally diverted from strategic missions to carry out air support and interdiction missions. It supported Operation Overlord, the invasion of Normandy by attacking transportation targets, including bridges, along with airfields and strong points in France. On D Day, the squadron and the rest of the 446th Group led the first heavy bomber mission of the day. The 446th aided ground forces at Caen and Saint-Loduring July by hitting bridges, gun batteries, and enemy troops. During Operation Market Garden, the attempt to seize a bridgehead across the Rhine in the Netherlands, the 704th dropped supplies to allied troops near Nijmegen. It struck lines of communications during the Battle of the Bulge. During Operation Varsity in March 1945, it supplied ground and airborne troops near Wesel. The squadron flew its last combat mission on 25 April 1945 against Salzburg, Austria. The group had flown 273 missions and had lost 58 aircraft during the war,
. Links: a. Allies of World War II b. Wesel c. Operation Market Garden d. Air Support.
Output: c
The passage describes the 704th's actions during Operation Market Garden.

New input case for you: Question: What is the difference in age between Campbell and his brother-in-law? Passage:He was born at Bedford Square, London, January 4, 1809. He grew up in an affluent family, the fifth of the six children born to Duncan Campbell (d.1815), who had made a fortune in the West Indies, and Harriet (d.1817), daughter of Robert Young of Auchenshcoch. He was the grandson of Alexander Campbell (1710-1760), 11th Laird of Inverawe, Argyll, descended from Archibald Campbell of Inverawe. His brother, Colonel James Campbell, built New Inverawe, today known as Ardanaiseig Hotel. He was a brother-in-law of Sir Alexander Spearman 1st Bt., of Hanwell, and his sister-in-law was a niece of Lt.-General Sir James Campbell, 1st Bt., of Inverneill. In 1832, he graduated from the Royal Military Academy Sandhurst and was appointed Captain of the Royal Scots and aide-de-camp to Lieutenant-General Campbell. He transferred to the 1st The Royal Dragoons and then joined the 7th Queen's Own Hussars, serving in the Near East.
Links: a. Clan Campbell b. Aide-de-camp c. Spearman baronets d. Bedford Square
Output:
c