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.

[Q]: Passage: A comprehensive school is a state school that does not select its intake on the basis of academic achievement or aptitude. This is in contrast to the selective school system, where admission is restricted on the basis of selection criteria. The term is commonly used in relation to England and Wales, where comprehensive schools were introduced on an experimental basis in the 1940s and became more widespread from 1965. About 90% of British secondary school pupils now attend comprehensive schools. They correspond broadly to the public high school in the United States and Canada and to the German Gesamtschule.[citation needed] Question: What kind of school system uses academic success to judge admissions?
[A]: selective school system


[Q]: Passage: Israel retaliated against Egyptian shelling with commando raids, artillery shelling and air strikes. This resulted in an exodus of civilians from Egyptian cities along the Suez Canal's western bank. Nasser ceased all military activities and began a program to build a network of internal defenses, while receiving the financial backing of various Arab states. The war resumed in March 1969. In November, Nasser brokered an agreement between the PLO and the Lebanese military that granted Palestinian guerrillas the right to use Lebanese territory to attack Israel. Question: Who would get to attack Israel from Lebanon?
[A]: Palestinian guerrillas


[Q]: Passage: In general relativity, a vanishing stress-energy tensor implies, through Einstein field equations, the vanishing of all the components of the Ricci tensor. Vacuum does not mean that the curvature of space-time is necessarily flat: the gravitational field can still produce curvature in a vacuum in the form of tidal forces and gravitational waves (technically, these phenomena are the components of the Weyl tensor). The black hole (with zero electric charge) is an elegant example of a region completely "filled" with vacuum, but still showing a strong curvature. Question: What has no electric charge?
[A]:
black hole