Problem: The Portuguese explorer Diogo Cao reached the mouth of the Congo in 1484. Commercial relationships quickly grew between the inland Bantu kingdoms and European merchants who traded various commodities, manufactured goods, and people captured from the hinterlands. After centuries as a major hub for transatlantic trade, direct European colonization of the Congo river delta began in the late 19th century, subsequently eroding the power of the Bantu societies in the region.
What was responsible for the power of Bantu societies growing in the late 19th century?
---
Answer: unanswerable

Problem: Widowed in 1861, the grief-stricken Queen withdrew from public life and left Buckingham Palace to live at Windsor Castle, Balmoral Castle and Osborne House. For many years the palace was seldom used, even neglected. In 1864, a note was found pinned to the fence of Buckingham Palace, saying: "These commanding premises to be let or sold, in consequence of the late occupant's declining business." Eventually, public opinion forced the Queen to return to London, though even then she preferred to live elsewhere whenever possible. Court functions were still held at Windsor Castle, presided over by the sombre Queen habitually dressed in mourning black, while Buckingham Palace remained shuttered for most of the year.
What happened to Buckingham after Queen Victoria left?
---
Answer: palace was seldom used, even neglected

Problem: In May 2005, the first high definition video conferencing systems, produced by LifeSize Communications, were displayed at the Interop trade show in Las Vegas, Nevada, able to provide video at 30 frames per second with a 1280 by 720 display resolution. Polycom introduced its first high definition video conferencing system to the market in 2006. As of the 2010s, high definition resolution for videoconferencing became a popular feature, with most major suppliers in the videoconferencing market offering it.
What did LifeSize Communications introduce in 2006?
---
Answer:
unanswerable