How did European nations increasingly form alliances in the early 1900s?

-to promote travel

-to provide a balance of power

-to ensure open borders

-to make it easy to found colonies

The correct answer is to provide a balance of power.

Indeed, in 1900, Europe was divided into several competing Empires such as the British Empire, the Dutch Empire, the French Empire, the Russian Empire, etc. Depending on a series of geopolitical factors such as history, language, culture, economy, border disputes and of course colonization, these empires had diverging and converging interests that pitted them against each other.

In order to prevail, these Empires formed alliances with other empires based on common interests. France and Britain had the Entente Cordiale which united them against The German and Austrian Empires. France also had an alliance with the Russian Empire. The German Empire formed an alliance with the Austrian Empire and with the Turks of the Ottoman Empire which although not European, occupied portions of Europe, mainly in north eastern Greece. This precarious equilibrium lasted until the onset of WWI.

The Answer too this question is B