In this task, you are given a question and a context passage. You have to answer the question based on the given passage.

[Q]: what is the second time period mentioned?, Context: European colonialism in the Sahara began in the 19th century. France conquered the regency of Algiers from the Ottomans in 1830, and French rule spread south from Algeria and eastwards from Senegal into the upper Niger to include present-day Algeria, Chad, Mali then French Sudan including Timbuktu, Mauritania, Morocco (1912), Niger, and Tunisia (1881). By the beginning of the 20th century, the trans-Saharan trade had clearly declined because goods were moved through more modern and efficient means, such as airplanes, rather than across the desert.
[A]: 1830


[Q]: Why could there be reasonable doubt about the validity of what was stated that she said?, Context: In May 2007, The Daily Telegraph, citing unnamed sources, reported that the Queen was "exasperated and frustrated" by the policies of the British Prime Minister, Tony Blair, that she was concerned the British Armed Forces were overstretched in Iraq and Afghanistan, and that she had raised concerns over rural and countryside issues with Blair. She was, however, said to admire Blair's efforts to achieve peace in Northern Ireland. On 20 March 2008, at the Church of Ireland St Patrick's Cathedral, Armagh, the Queen attended the first Maundy service held outside England and Wales. At the invitation of the Irish President, Mary McAleese, the Queen made the first state visit to the Republic of Ireland by a British monarch in May 2011.
[A]: unnamed sources


[Q]: This acronym maintains this, a nationwide network of libraries dedicated to preserving and making available the documents of U.S. presidents?, Context: NARA also maintains the Presidential Library system, a nationwide network of libraries for preserving and making available the documents of U.S. presidents since Herbert Hoover. The Presidential Libraries include:
[A]:
Presidential Library system