In this task, you're given a question, along with a context passage. The passage will not have a direct answer to the question, but can include some information and a clue for the answer. Assuming you can only obtain information about one entity in the passage, your job is to determine whether information from the passage can be used to answer the question. Indicate your choice as `a` for Yes or `b` for No.

Example Input: Question: Which US Air Force plane that was shot down in Yugoslavia is the fastest? Passage:An important portion of the 1999 war between Yugoslavia and the NATO coalition involved combat between the Yugoslav Air Force, which was the predecessor of today's Serbian Air Force, and the opposing air forces of NATO. United States Air Force F-15s and F-16s flying mainly from Italian air force bases attacked the defending Yugoslav fighters—usually MiG-29s, which were in bad shape, due to lack of spare parts and maintenance. A total of six Yugoslav MiG-29s were shot down in 1999, of which three were shot down by USAF F-15s, one by a USAF F-16, and one by a RNAF F-16. One aircraft, according to a Serbian documentary, was hit by friendly fire from the ground. Another four were destroyed on the ground. During the course of the air war, Yugoslav anti-aircraft defenses downed a USAF F-16C and an F-117 Nighthawk, the first stealth aircraft to ever be shot down in combat.

Example Output: b

Example Input: Question: How long was the fortification that the German Army retreated to? Passage:Adair fought in the First World War. He joined the British Army, receiving his commission as a probationary second lieutenant on 2 May 1916 in the 5th (Reserve) Battalion of the Grenadier Guards. From January 1917 onwards he served in the trenches of the Western Front in France and Belgium as part of the 2nd Company, 3rd Battalion, Grenadier Guards, with the rank of lieutenant. The battalion was part of the 2nd Guards Brigade of the Guards Division. Adair's first major battle was in the pursuit of the retreating German Army to the Hindenburg Line. The division then took part in the Battle of Passchendaele. Adair, however, took no part in the battle, due to an injury sustained in a bicycle accident in early July 1917. He returned to the battalion in January 1918.

Example Output: b

Example Input: Question: What age was Dud Dudley when a patent was granted to him? Passage:The first production of tinplate was probably in Bohemia, from where the trade spread to Saxony, and was well-established there by the 1660s. Andrew Yarranton and Ambrose Crowley (a Stourbridge blacksmith and father of the more famous Sir Ambrose) visited Dresden in 1667 and found out how it was made. In doing so, they were sponsored by various local ironmasters and people connected with the project to make the river Stour navigable. In Saxony, the plates were forged, but when they conducted experiments on their return to England, they tried rolling the iron. This led to the ironmasters Philip Foley and Joshua Newborough (two of the sponsors) in 1670 erecting a new mill, Wolverley Lower Mill (or forge). This contained three shops, one being a slitting mill (which would serve as a rolling mill), and the others were forges. In 1678 one of these was making frying pans and the other drawing out blooms made in finery forges elsewhere. It is likely that the intention was to roll the plates and then finish them under a hammer, but the plan was frustrated by one William Chamberlaine renewing a patent granted to him and Dud Dudley in 1662.

Example Output:
b