After 1900, Great Britain Discarded Her "Splendid Isolation" and Became

After 1900, Great Britain discarded her "splendid isolation" and became willing to enter alliances because:

A) the Fashoda crisis and the Boer War revealed how isolated Britain was in Europe.
B) the French proved willing to resolve old colonial disputes.
C) Germany's naval construction program caused the Germans profound worry.
D) All of these are correct.