I think the answer is (D)
1927 was a fundamental year and motion pictures because it brought the first films with sound.
Europe, has more advances in technology in warfare, transportations. Also their governments are strong and stable due to ones careful rule.
But the real reason for European dominant is because they really and I mean really focus on their militaristic aspect as which they relied on for stability, conquest, and glory because thousands of years, Kings and some Queens are tought the ways of war and how war can give more than just territory and as a matter of fact Kings had trained themselves in Europe for milania, so not just did Kings evolve but the technology to fight among themselves were drastically improved as well.
I hope I was a little help to you
