Answer: B is correct ...both France and UK were superpowers in decline already before WW II but it was after WW II when the post-war consequences pushed them to decolonization. Global power moved to USSR and USA.
Explanation: during XVIII and XIX centuries there is still rivalry between France and UK but both powers are already in decline (UK started losing its power already during the 2nd half of the 19th century. Russia was too underdeveloped and USA still busy with their own territory and integrity. USA entered global stage with Spanish-American War and after that Great War. Entering in the WW II (Pearl Harbor 1941) make USA world superpower. UK and France are loosing their ground and today there is a post-imperial trauma.