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.

[EX Q]: 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.
[EX A]: What factor forced the French to retreat to Metz?

[EX Q]: Roofs are traditionally constructed from Alpine rocks such as pieces of schist, gneiss or slate. Such chalets are typically found in the higher parts of the valleys, as in the Maurienne valley in Savoy, where the amount of snow during the cold months is important. The inclination of the roof cannot exceed 40%, allowing the snow to stay on top, thereby functioning as insulation from the cold. In the lower areas where the forests are widespread, wooden tiles are traditionally used. Commonly made of Norway spruce, they are called "tavaillon". The Alpine regions are multicultural and linguistically diverse. Dialects are common, and vary from valley to valley and region to region. In the Slavic Alps alone 19 dialects have been identified. Some of the French dialects spoken in the French, Swiss and Italian alps of Aosta Valley derive from Arpitan, while the southern part of the western range is related to Old Provençal; the German dialects derive from Germanic tribal languages. Romansh, spoken by two percent of the population in southeast Switzerland, is an ancient Rhaeto-Romanic language derived from Latin, remnants of ancient Celtic languages and perhaps Etruscan.
[EX A]: What are roofs traditionally constructed from? 

[EX Q]: Similarly, forensic anthropologists draw on highly heritable morphological features of human remains (e.g. cranial measurements) to aid in the identification of the body, including in terms of race. In a 1992 article, anthropologist Norman Sauer noted that anthropologists had generally abandoned the concept of race as a valid representation of human biological diversity, except for forensic anthropologists. He asked, "If races don't exist, why are forensic anthropologists so good at identifying them?" He concluded:
[EX A]:
What morphological features do forensic anthropologists draw on?