It’s B. I had the same assignment and I got it right ^w^
There were 7 leaders
-Eamon de Valera
-Arthur Griffith
-david Lloyd George
- lord French
-lord fitzAlan
-Ian macpherson
-hamar greenwood
The affect was being able to attack from air,sea,and land which also lead to surprise attacks
It is updated every year. Hope this helps!
