This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.

The timing of migration seems to be controlled primarily by changes in day length. Migrating birds navigate using celestial cues from the sun and stars, the earth's magnetic field, and probably also mental maps.
What causes the timing of migration?

During the Hungnam evacuation, about 193 shiploads of UN Command forces and matériel (approximately 105,000 soldiers, 98,000 civilians, 17,500 vehicles, and 350,000 tons of supplies) were evacuated to Pusan. The SS Meredith Victory was noted for evacuating 14,000 refugees, the largest rescue operation by a single ship, even though it was designed to hold 12 passengers. Before escaping, the UN Command forces razed most of Hungnam city, especially the port facilities; and on 16 December 1950, President Truman declared a national emergency with Presidential Proclamation No. 2914, 3 C.F.R. 99 (1953), which remained in force until 14 September 1978.[b] The next day (17 December 1950) Kim Il-sung was deprived of the right of command of KPA by China. After that, the leading part of the war became the Chinese army. Following that, on 1 February 1951, United Nations General Assembly adopted a draft resolution condemning China as an aggressor in the Korean War.
What was the name of the ship responsible for undertaking the largest rescue operation by a single ship?

Plymouth's gross value added (a measure of the size of its economy) was 5,169 million GBP in 2013 making up 25% of Devon's GVA. Its GVA per person was £19,943 and compared to the national average of £23,755, was £3,812 lower. Plymouth's unemployment rate was 7.0% in 2014 which was 2.0 points higher than the South West average and 0.8 points higher than the average for Great Britain (England, Wales and Scotland).
What percentage of Devon's GVA does Plymouth comprise in 2013?