Correct answer is a: Europeans arrived in the America
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Explanation:
A is the correct answer as in 1492 Christopher Columbo with his three ships arrived in the New World. From that period on Europeans started colonizing this area, which forever changed the history of this area. Some Native tribes even disappeared due to this fact.
All other answers are false, as they are not based on historical facts.
Persia's standing army was an important factor in Persia's rapid growth because of the elite soldiers within the standing army. They were known as the "Immortals" and tasked to maintain order from within and the outside.
