Final answer:
During World War I, Big Bertha was a heavy artillery gun, not a tank, machine gun, or submarine. The British introduced tanks as new military technology, while the Germans deployed submarines, known as U-boats, which posed great threats at sea. Artillery was the leading cause of casualties during the war.
Step-by-step explanation:
During World War I, Big Bertha was b) a heavy artillery gun. Developed by the German arms manufacturer Krupp, Big Bertha was a 420-mm howitzer used extensively from the beginning to the conclusion of the war. Artillery became a key tool for fighting, with advancements in firepower and the ability to move such large guns necessitating rail transport and sometimes special railroad construction. Contrary to Big Bertha, the British introduced d) tanks as a new type of military technology during World War I, which revolutionized land warfare and helped to break the stalemate of trench warfare.
The naval scene in World War I saw the introduction of submarines, which brought a new stealth capability to naval combat. German submarines, known as Unterseeboots or U-boats, posed significant threats to merchant and military ships alike before the Allies developed effective countermeasures such as convoys and naval escorts.
While machine guns had already changed the nature of warfare with their rapid firepower, and Germany had attempted to build a powerful navy to match the British Dreadnought, it was the artillery that remained the leading killer during the Great War, resulting in the majority of battlefield casualties.