The United States Japan and France are classified as developed as countries Because

if you link into the demographic transition model(don't know if you have heard of it but ) the birth rates are much lower in developed countries but also think about how useful theses countries are t the rest of the world - japan export many equipment , cars, electronics - Toyota etc., the US  have the biggest silicon valley used for electronic - apple and other tech companies use them - think of it that way

Explanation:

show me the image i cant tell

the only other powers were germany russia and uk and they were too busy fighting each other wearing each other down   that the us was becoming strong and they were becoming weaker