In Which of the Following Is There a Balance of Power

In which of the following is there a balance of power?

A) When the United States was the sole superpower in the 1990s.
B) When China refrains from taking over Taiwan.
C) After World War II,when the Allies defeated the Axis powers.
D) When Germany and the Soviet Union agreed to invade and divide Poland between them.
E) When the United States and the Soviet Union had roughly equal military strength.