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.

[Q]: The primary physiological cue for migration are the changes in the day length. These changes are also related to hormonal changes in the birds. In the period before migration, many birds display higher activity or Zugunruhe (German: migratory restlessness), first described by Johann Friedrich Naumann in 1795, as well as physiological changes such as increased fat deposition. The occurrence of Zugunruhe even in cage-raised birds with no environmental cues (e.g. shortening of day and falling temperature) has pointed to the role of circannual endogenous programs in controlling bird migrations. Caged birds display a preferential flight direction that corresponds with the migratory direction they would take in nature, changing their preferential direction at roughly the same time their wild conspecifics change course.
[A]: What is the primary cue for migration?

[Q]: On 1 September 1939, two days before Britain declared war on Germany, the station was taken off air with little warning; the government was concerned that the VHF transmissions would act as a beacon to enemy aircraft homing in on London. Also, many of the television service's technical staff and engineers would be needed for the war effort, in particular on the radar programme. The last programme transmitted was a Mickey Mouse cartoon, Mickey's Gala Premier (1933), which was followed by test transmissions; this account refuted the popular memory according to which broadcasting was suspended before the end of the cartoon.
[A]: What did the British fear could provide guidance to the German air force?

[Q]: Many instruments today associated with popular music filled important roles in early classical music, such as bagpipes, vihuelas, hurdy-gurdies, and some woodwind instruments. On the other hand, instruments such as the acoustic guitar, once associated mainly with popular music, gained prominence in classical music in the 19th and 20th centuries.
[A]:
In what did the bagpipe fill an important role?