Extract the answer to the question from the following context. Question: What is needed to generate energy? Context: According to a 2011 projection by the International Energy Agency, solar power plants may produce most of the world's electricity within 50 years, significantly reducing the emissions of greenhouse gases that harm the environment. The IEA has said: "Photovoltaic and solar-thermal plants may meet most of the world's demand for electricity by 2060 and half of all energy needs with wind, hydropower and biomass plants supplying much of the remaining generation". "Photovoltaic and concentrated solar power together can become the major source of electricity".
Ans: solar

Extract the answer to the question from the following context. Question: What made the Low Countries feel that the document was the only way out? Context: In 1579 a number of the northern provinces of the Low Countries signed the Union of Utrecht, in which they promised to support each other in their defence against the Spanish army. This was followed in 1581 by the Act of Abjuration, the declaration of independence of the provinces from Philip II.
Ans: Spanish army

Extract the answer to the question from the following context. Question: Which powers would be played against each other? Context: In some rare cases, such as with Ethiopia and Qing Dynasty China, the local governments were able to use the treaties to at least mitigate the impact of European colonization. This involved learning the intricacies of European diplomatic customs and then using the treaties to prevent a power from overstepping their agreement or by playing different powers against each other.
Ans: European

Extract the answer to the question from the following context. Question: After the fall what were the of Constantinople? Context: Following the Fall of Constantinople on 29 May 1453, many Greeks sought better employment and education opportunities by leaving for the West, particularly Italy, Central Europe, Germany and Russia. Greeks are greatly credited for the European cultural revolution, later called, the Renaissance. In Greek-inhabited territory itself, Greeks came to play a leading role in the Ottoman Empire, due in part to the fact that the central hub of the empire, politically, culturally, and socially, was based on Western Thrace and Greek Macedonia, both in Northern Greece, and of course was centred on the mainly Greek-populated, former Byzantine capital, Constantinople. As a direct consequence of this situation, Greek-speakers came to play a hugely important role in the Ottoman trading and diplomatic establishment, as well as in the church. Added to this, in the first half of the Ottoman period men of Greek origin made up a significant proportion of the Ottoman army, navy, and state bureaucracy, having been levied as adolescents (along with especially Albanians and Serbs) into Ottoman service through the devshirme. Many Ottomans of Greek (or Albanian or Serb) origin were therefore to be found within the Ottoman forces which governed the provinces, from Ottoman Egypt, to Ottomans occupied Yemen and Algeria, frequently as provincial governors.
Ans: mainly Greek