instruction:
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.
question:
With the defeat of Marshal Bazaine's Army of the Rhine at Gravelotte, the French were forced to retire to Metz, where they were besieged by over 150,000 Prussian troops of the First and Second Armies. Napoleon III and MacMahon formed the new French Army of Châlons, to march on to Metz to rescue Bazaine. Napoleon III personally led the army with Marshal MacMahon in attendance. The Army of Châlons marched northeast towards the Belgian border to avoid the Prussians before striking south to link up with Bazaine. The Prussians, under the command of Field Marshal Count Helmuth von Moltke, took advantage of this maneuver to catch the French in a pincer grip. He left the Prussian First and Second Armies besieging Metz, except three corps detached to form the Army of the Meuse under the Crown Prince of Saxony. With this army and the Prussian Third Army, Moltke marched northward and caught up with the French at Beaumont on 30 August. After a sharp fight in which they lost 5,000 men and 40 cannons, the French withdrew toward Sedan. Having reformed in the town, the Army of Châlons was immediately isolated by the converging Prussian armies. Napoleon III ordered the army to break out of the encirclement immediately. With MacMahon wounded on the previous day, General Auguste Ducrot took command of the French troops in the field.
answer:
What factor forced the French to retreat to Metz?


question:
When the GHMC was created in 2007, the area occupied by the municipality increased from 175 km2 (68 sq mi) to 650 km2 (250 sq mi). Consequently, the population increased by 87%, from 3,637,483 in the 2001 census to 6,809,970 in the 2011 census, 24% of which are migrants from elsewhere in India,:2 making Hyderabad the nation's fourth most populous city. As of 2011[update], the population density is 18,480/km2 (47,900/sq mi). At the same 2011 census, the Hyderabad Urban Agglomeration had a population of 7,749,334, making it the sixth most populous urban agglomeration in the country. The population of the Hyderabad urban agglomeration has since been estimated by electoral officials to be 9.1 million as of early 2013 but is expected to exceed 10 million by the end of the year. There are 3,500,802 male and 3,309,168 female citizens—a sex ratio of 945 females per 1000 males, higher than the national average of 926 per 1000. Among children aged 0–6 years, 373,794 are boys and 352,022 are girls—a ratio of 942 per 1000. Literacy stands at 82.96% (male 85.96%; female 79.79%), higher than the national average of 74.04%. The socio-economic strata consist of 20% upper class, 50% middle class and 30% working class.
answer:
What was the area of Hyderabad before the GHMC?


question:
New Delhi has a population of 249,998. Hindi and Punjabi are the most widely spoken languages in New Delhi and the lingua franca of the city. English is primarily used as the formal language by business and government institutes. New Delhi has a literacy rate of 89.38% according to 2011 census, which is highest in Delhi.
answer:
What is the population of New Delhi?