This task is about writing a correct answer for the reading comprehension task. Based on the information provided in a given passage, you should identify the shortest continuous text span from the passage that serves as an answer to the given question. Avoid answers that are incorrect or provides incomplete justification for the question.
--------
Question: Passage: In the last two decades of the 18th century, the theory of polygenism, the belief that different races had evolved separately in each continent and shared no common ancestor, was advocated in England by historian Edward Long and anatomist Charles White, in Germany by ethnographers Christoph Meiners and Georg Forster, and in France by Julien-Joseph Virey. In the US, Samuel George Morton, Josiah Nott and Louis Agassiz promoted this theory in the mid-nineteenth century. Polygenism was popular and most widespread in the 19th century, culminating in the founding of the Anthropological Society of London (1863) during the period of the American Civil War, in opposition to the Ethnological Society, which had abolitionist sympathies. Question: In what century was polygenism most widespread?

Answer: 19th century

Question: Passage: During the Franco-Prussian War and the Siege of Strasbourg, the city was heavily bombarded by the Prussian army. The bombardment of the city was meant to break the morale of the people of Strasbourg. On 24 and 26 August 1870, the Museum of Fine Arts was destroyed by fire, as was the Municipal Library housed in the Gothic former Dominican church, with its unique collection of medieval manuscripts (most famously the Hortus deliciarum), rare Renaissance books, archeological finds and historical artifacts. The gothic cathedral was damaged as well as the medieval church of Temple Neuf, the theatre, the city hall, the court of justice and many houses. At the end of the siege 10,000 inhabitants were left without shelter; over 600 died, including 261 civilians, and 3200 were injured, including 1,100 civilians. Question: Who bombarded the city of Strasbourg?

Answer: Prussian army

Question: Passage: The line of imams of the Mustali Ismaili Shia Muslims (also known as the Bohras/Dawoodi Bohra) continued up to Aamir ibn Mustali. After his death, they believe their 21st Imam Taiyab abi al-Qasim went into a Dawr-e-Satr (period of concealment) that continues to this day. In the absence of an imam they are led by a Dai-al-Mutlaq (absolute missionary) who manages the affairs of the Imam-in-Concealment until re-emergence of the Imam from concealment. Dawoodi Bohra's present 53rd Da'i al-Mutlaq is His Holiness Syedna Mufaddal Saifuddin (TUS) who succeeded his predessor the 52nd Da'i al-Mutlaq His Holiness Syedna Mohammed Burhanuddin (RA). Furthermore, there has been a split in the Dawoodi Bohra sect which has led to the formation of Qutbi Bohra sect which was formed and led by Khuzaima Qutbuddin. Question: What do Bohras believe happened to Taiyab abi al-qasim?

Answer:
went into a Dawr-e-Satr