To expand their empires, imperialist countries in the 1800s preferred to take over other imperialist countries with experienced labor forces. industrially undeveloped countries rich in natural resources. other imperialist countries that needed raw materials. industrially undeveloped countries that needed resources.

The correct answer is the second one: industrially undeveloped countries rich in natural resources.

During the 19th century, many Imperialist countries from Europe were going through the Industrial Revolution, which means their economies were focusing on the production of manufactured goods. To follow this path, they needed a great number of raw materials that they couldn't get from their natural resources. For that reasons, they started a large colonial campaign, especially in Africa, in order to conquer new land and exploit vast natural resources to fuel their industrial economies. In 1884, in the Berlin Conference, the European industrial powers divided Africa for their exploitation according to their imperial interests and needs.