Answer:
It was the main cause as all great European powers wanted to spread their imperialistic and colonial power.
Step-by-step explanation:
After Italy and Germany were unified European political scene was totally different. Old powers felt threatened by the rise of these countries, while on the other side, Germany and Italy, together with Austria-Hungary wanted to strengthen their role.
After the Berlin Conference it was obvious that France and Britain had dominance in the colonies, therefore the so-called Central Powers wanted to rearrange this.
Entente powers didn't wanted to change their stance and it was just a question of time when the world will begin.