Which policy did Gorbachev implement that focused on political transparency?

The policy that Gorbachev implemented focusing on political transparency is indeed Glasnost. Glasnost translates to "openness" in Russian and was introduced in the mid-1980s as part of Gorbachev's reforms. The aim of this policy was to promote more freedom of expression, reduce censorship, and encourage a more transparent government. It allowed for greater freedom of the press and public discussion, ultimately leading to a more informed populace and increased public participation in political discourse.

By encouraging openness, Glasnost laid the groundwork for significant changes within the Soviet Union, including the ability for citizens to express dissatisfaction with the government, which contributed to the eventual dissolution of the Soviet Union. Through Glasnost, Gorbachev sought to improve the legitimacy of the Communist Party by acknowledging past issues and fostering a more accountable political environment.

The other choices represent different concepts: Perestroika refers to economic restructuring and reform initiated by Gorbachev, Detente describes the easing of strained relations, especially between the U.S. and the Soviet Union during the Cold War, and Solidarity was a labor and political movement in Poland that played a crucial role in opposing communist rule but is not directly related to Gorbachev's policies.