In this task, you're given a passage, further information available on a particular linked term from the statement, and an answer term. Your job is to generate a question that can use the information provided to obtain the given answer. You should use the information on both passage and link information to create the question. Note that the answer to the question should be exactly the given answer, and if the answer is none, the answer to the question shouldn't be obtainable from the passage or linked information.
One example is below.
Q: 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-Lo during 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,
. Link Information: Operation Market Garden was a failed World War II military operation fought in the Netherlands from 17 to 25 September 1944. Answer: from 17 to 25 September 1944
A: When did the operation during which the 704th dropped supplies to allied troops near Nijmegen begin?
Rationale: The passage describes the 704th's actions during Operation Market Garden, and the answer specifies when the operation happened.
Q: Passage: Serco operates the Santander Cycles scheme (for Transport for London) and the NorthLink Ferries Northern Isles lifeline ferry service in Scotland. Serco also has a joint venture with Abellio, the international arm of Dutch national rail operator Nederlandse Spoorwegen, to operate passenger trains in the UK. Serco-Abellio has a 25-year concession for Merseyrail in Liverpool until 2028 and operated the Northern Rail franchise from December 2004 until March 2016. Serco's Home Affairs division, run by Tom Riall, also operates speed camera systems throughout the UK and, until November 2013, designed, wrote and tested the software that controls the matrix message signs, signals, emergency roadside telephones (SOS) and traffic monitoring on England's motorway network including, until 2011, the National Traffic Control Centre. It previously operated the Docklands Light Railway.
Link Information: Since July 2012, it has been operated by international services company Serco. Answer: 7
A:
How many years has Serco been operating the NorthLink Ferries?