Given the task definition and input, reply with output. 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.

Passage: Donaldson was born in Islington, London, and was an England schoolboy international before beginning his football career with Arsenal. He was a member of their 1971 FA Youth Cup-winning side, but never broke through to the first team. In June 1973, he transferred to Second Division club Millwall for 5,000. The team were relegated in 1975, and Donaldson helped them achieve promotion back to the Second Division in 197576, and made 258 appearances in all competitions over a six-and-a-half-year period. He acted as an emergency goalkeeper three times during his Millwall career. He spent the summer of 1979 with the Los Angeles Skyhawks of the American Soccer League, and on 5 February 1980, signed for Second Division Cambridge United for a fee of 50,000. He made 132 league appearances for Cambridge and was featured in a 2002 book, Cambridge United: 101 Golden Greats. In 1984, he moved on to Royston Town of the Isthmian League.
Link Information:

Islington is the most densely populated borough in the UK according to the 2011 census, with a population density of 138.7 people per hectare, compared to an average of 52.0 for London. Answer: 138.7
How big is the city Donaldson was born in?