Input: Article: The official published membership statistics, such as those mentioned above, include only those who submit reports for their personal ministry; official statistics do not include inactive and disfellowshipped individuals or others who might attend their meetings. As a result, only about half of those who self-identified as Jehovah's Witnesses in independent demographic studies are considered active by the faith itself. The 2008 US Pew Forum on Religion & Public Life survey found a low retention rate among members of the religion: about 37% of people raised in the religion continued to identify themselves as Jehovah's Witnesses.

Now answer this question: Where do the officially published membership statistics come from?

Output: those who submit reports for their personal ministry

Input: Article: Stone and brick became the city's building materials of choice after the construction of wood-frame houses was limited in the aftermath of the Great Fire of 1835. A distinctive feature of many of the city's buildings is the wooden roof-mounted water towers. In the 1800s, the city required their installation on buildings higher than six stories to prevent the need for excessively high water pressures at lower elevations, which could break municipal water pipes. Garden apartments became popular during the 1920s in outlying areas, such as Jackson Heights.

Now answer this question: In the 19th century, New York city required water towers in the roofs of buildings that were more than how many stories tall?

Output: six

Input: Article: Colonial records of French and Spanish slave ships and sales, and plantation records in all the former colonies, often have much more information about slaves, from which researchers are reconstructing slave family histories. Genealogists have begun to find plantation records, court records, land deeds and other sources to trace African-American families and individuals before 1870. As slaves were generally forbidden to learn to read and write, black families passed along oral histories, which have had great persistence. Similarly, Native Americans did not generally learn to read and write English, although some did in the nineteenth century. Until 1930, census enumerators used the terms free people of color and mulatto to classify people of apparent mixed race. When those terms were dropped, as a result of the lobbying by the Southern Congressional bloc, the Census Bureau used only the binary classifications of black or white, as was typical in segregated southern states.

Now answer this question: What has helped geneologists researching slaves?

Output:
Colonial records of French and Spanish slave ships and sales, and plantation records in all the former colonies