Answer:
A. European rivalries over colonial territory led to nationalistic tension among these states.
Step-by-step explanation:
Imperialism contributed to the start of WWI in such that the "European rivalries over colonial territory led to nationalistic tension among these states."
Imperialism is a term used in describing the strategy of a particular country exercising its power and influence to colonize other countries or nations using military force.
Hence, imperialism contributed to the start of WWI when the likes of Britain, Germany, and France tried to expand their empires, which led to a rise in tensions as they fought for resources among European countries.