Final answer:
The correct answer is option A. Imperialism.
Step-by-step explanation:
The policy where one country takes over another country is known as Imperialism. This involves a stronger nation seeking to dominate other countries politically, socially, and economically. Historically, imperialism was a driving force behind the establishment and expansion of empires, where the imperial powers exerted control over their colonies for various benefits such as accessing resources, establishing trade, and demonstrating military and political might.
A clear example of imperialism was the European colonialism that spanned from the 15th to the 20th century. During this period, European powers like Great Britain and France expanded their empires by colonizing parts of Asia, Africa, and the Americas. They often used military conquest and exercised control over these territories to secure economic gain and prevent competition from other imperial powers.