This political party was in power from 1917 until 1990 in the soviet union.

The political party in power from 1917 until 1990 in the Soviet Union is known as the Communist party.

This party helped to create the system in which the government had significant control of the economy, agriculture, and individual rights in the Soviet Union. This control was also executed in the satellite nations controlled by the Soviet Union during this time period as well.
 

C) to abolish the practice of slavery within the United States.