Upon which idea is glasnost based

The correct answer is openness of speech and expression

At first, glasnost was about having transparent court hearings and similar things where people could know if someone was being trialed politically. It evolved into genuine transparency as it created things like freedom of the press and freedom from political prosecution and similar things which were a common thing back then.

Glasnost is an idea based on less government control over Soviet society. This term translates to "openness" and allowed for the media to write stories without needing the governments approval to publish them.

Along with this, the policy of glasnost gave more social freedoms to individual citizens.

Citizens who held negative views about the government or did not follow the most popular religion in the Soviet Union were now able to express their views without fear of punishment from the Soviet government.