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.

[EX Q]: Passage: Red is the traditional color of warning and danger. In the Middle Ages, a red flag announced that the defenders of a town or castle would fight to defend it, and a red flag hoisted by a warship meant they would show no mercy to their enemy. In Britain, in the early days of motoring, motor cars had to follow a man with a red flag who would warn horse-drawn vehicles, before the Locomotives on Highways Act 1896 abolished this law. In automobile races, the red flag is raised if there is danger to the drivers. In international football, a player who has made a serious violation of the rules is shown a red penalty card and ejected from the game. Question: What is a football player shown before being ejected from a match?
[EX A]: a red penalty card

[EX Q]: Passage: The strategy behind the formation of the Warsaw Pact was driven by the desire of the Soviet Union to dominate Central and Eastern Europe. This policy was driven by ideological and geostrategic reasons. Ideologically, the Soviet Union arrogated the right to define socialism and communism and act as the leader of the global socialist movement. A corollary to this idea was the necessity of intervention if a country appeared to be violating core socialist ideas and Communist Party functions, which was explicitly stated in the Brezhnev Doctrine. Geostrategic principles also drove the Soviet Union to prevent invasion of its territory by Western European powers. Question: The Soviet Union feared invasion from which potential enemy?
[EX A]: Western Europe

[EX Q]: Passage: In 1963, Ralph J. Roberts in conjunction with his two business partners, Daniel Aaron and Julian A. Brodsky, purchased American Cable Systems as a corporate spin-off from its parent, Jerrold Electronics, for US $500,000. At the time, American Cable was a small cable operator in Tupelo, Mississippi, with five channels and 12,000 customers. Storecast Corporation of America, a product placement supermarket specialist marketing firm, was purchased by American Cable in 1965. With Storecast being a Muzak client, American Cable purchased its first Muzak franchise of many in Orlando, Florida. Question: How many customers did ACS have when Roberts and his partners purchased it?
[EX A]:
12,000