<span>Sinking of the Lusitania
May 7, 1915
American gov said stop unrestricted warfare
germans said okay</span>
D. They used slaves for cheap labor.
Answer:
At the surface, the warm soup spreads out and cools, becoming denser. Gravity pulls this cooler, denser soup down to the bottom, where it is heated again and begins to rise.
(the soup is just an example)
Hope this help's sorry if i'm wrong.
Explanation:
They invaded africa with armies to capture slaves