The correct answer is D) glasnost.
Glasnost referred to a willingness of Soviet leaders to allow Western ideas to spread in the Soviet Union as a way to reform government and the economy.
Glasnost and perestroika were the two most important reformations made by Soviet leader Mikhail Gorbachev. Glasnost in English means "openness," and was the reformation that allowed people in the Soviet Union to have more freedom. Perestroika was the reformation and reconstruction of the USSR economy, opening its borders to foreign investors.