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.

Example Input: Passage: There are three ways an existing treaty can be amended. First, formal amendment requires State parties to the treaty to go through the ratification process all over again. The re-negotiation of treaty provisions can be long and protracted, and often some parties to the original treaty will not become parties to the amended treaty. When determining the legal obligations of states, one party to the original treaty and one a party to the amended treaty, the states will only be bound by the terms they both agreed upon. Treaties can also be amended informally by the treaty executive council when the changes are only procedural, technical change in customary international law can also amend a treaty, where state behavior evinces a new interpretation of the legal obligations under the treaty. Minor corrections to a treaty may be adopted by a procès-verbal; but a procès-verbal is generally reserved for changes to rectify obvious errors in the text adopted, i.e. where the text adopted does not correctly reflect the intention of the parties adopting it. Question: What must state parties to a treaty repeat to adopt a formal amendment to the treaty?
Example Output: the ratification process

Example Input: Passage: Goodluck Jonathan served as Nigeria's president till 16 April 2011, when a new presidential election in Nigeria was conducted. Jonathan of the PDP was declared the winner on 19 April 2011, having won the election with a total of 22,495,187 of the 39,469,484 votes cast, to stand ahead of Muhammadu Buhari from the main opposition party, the Congress for Progressive Change (CPC), which won 12,214,853 of the total votes cast. The international media reported the elections as having run smoothly with relatively little violence or voter fraud, in contrast to previous elections. Question: What was the main opposition political party in 2011?
Example Output: Congress for Progressive Change

Example Input: Passage: During his brief majority reign, Murad IV (1612–1640) reasserted central authority and recaptured Iraq (1639) from the Safavids. The resulting Treaty of Zuhab of that same year decisively parted the Caucasus and adjacent regions between the two neighbouring empires as it had already been defined in the 1555 Peace of Amasya. The Sultanate of women (1648–1656) was a period in which the mothers of young sultans exercised power on behalf of their sons. The most prominent women of this period were Kösem Sultan and her daughter-in-law Turhan Hatice, whose political rivalry culminated in Kösem's murder in 1651. During the Köprülü Era (1656–1703), effective control of the Empire was exercised by a sequence of Grand Viziers from the Köprülü family. The Köprülü Vizierate saw renewed military success with authority restored in Transylvania, the conquest of Crete completed in 1669, and expansion into Polish southern Ukraine, with the strongholds of Khotyn and Kamianets-Podilskyi and the territory of Podolia ceding to Ottoman control in 1676. Question: What years define the Köprülü Era?
Example Output:
1656–1703