Respuesta :
The correct answer is letter C.
This is because Ronald Reagan was first elected president of the United States 1980. After that, the concepts of "glasnost" and "perestroika" weren't introduced into the Soviet Union until the reign of Gorbachev. These policies were used as of 1985. The process of tearing down the Berlin Wall started in 1990 but did not officially end until 1992. These dates show that only C can be the correct answer.
This is because Ronald Reagan was first elected president of the United States 1980. After that, the concepts of "glasnost" and "perestroika" weren't introduced into the Soviet Union until the reign of Gorbachev. These policies were used as of 1985. The process of tearing down the Berlin Wall started in 1990 but did not officially end until 1992. These dates show that only C can be the correct answer.