The correct answers are A) overrode his veto of a resolution to limit presidential war powers, B) investigation of Watergate and D) impeachment recommendations.
The following three ways were used by Congress to keep Richard Nixon's power in check during the years he was president: overrode his veto of a resolution to limit presidential war powers, investigation of Watergate and impeachment recommendations.
The Senate of the United States established the Select Committee on Presidential Campaign Activities on February 7, 1973. Best known as the Senate Watergate Committee it was formed to investigate the Watergate incident. The committee was investigating illegal and unethical conduct during the election of 1972. So yes, three ways that were used by Congress to keep Richard Nixon's power in check during the years he was president were to override his veto of a resolution to limit presidential war powers, the investigation of Watergate and impeachment recommendations. In the end, Richard Nixon was impeached.
