Introduction:
The First World War, also known as the Great War, was a global conflict that began in 1914 and lasted until 1918. It was one of the deadliest wars in history, involving multiple countries and resulting in millions of deaths and significant political and social changes worldwide.

Explanation:
The correct answer to the question is option 'a) 1914'. Here's an explanation of why the First World War began in that year:

Background:
- In the late 19th and early 20th centuries, tensions were rising among European powers due to factors like imperialism, nationalism, militarism, and a complex web of alliances.
- The balance of power in Europe was fragile, with rivalries and rival alliances forming between major powers such as Germany, Austria-Hungary, Russia, France, and Britain.

The Assassination of Archduke Franz Ferdinand:
- On June 28, 1914, Archduke Franz Ferdinand of Austria-Hungary was assassinated in Sarajevo, Bosnia, by a Serbian nationalist named Gavrilo Princip.
- This event triggered a diplomatic crisis as Austria-Hungary believed Serbia was behind the assassination and issued an ultimatum, which Serbia rejected.

Outbreak of War:
- On July 28, 1914, Austria-Hungary declared war on Serbia, marking the beginning of hostilities.
- As Serbia was supported by Russia, a series of mobilizations and declarations of war followed, as various alliances were activated.
- Germany, supporting Austria-Hungary, declared war on Russia and its ally France. Germany also invaded Belgium to reach France quickly.
- Britain, allied with France, declared war on Germany in response to the violation of Belgian neutrality.

Global Conflict:
- With the declaration of war by major powers, the conflict quickly spread across Europe and eventually involved countries from around the world.
- The war saw the use of new weapons and tactics, including trench warfare, machine guns, poison gas, and tanks.
- Over the course of four years, the war resulted in significant casualties, devastation, and loss of life on all sides.

Conclusion:
The First World War began in 1914 after the assassination of Archduke Franz Ferdinand of Austria-Hungary. This event triggered a series of diplomatic crises and declarations of war among the major powers of Europe. The conflict quickly escalated into a global war, involving numerous countries and leading to massive casualties and destruction.