From 1800 to 1900, the land mass controlled by europe decreased increased remained unchanged unable to determine from information in lesson

The correct answer is - increased.

During the given time frame from 1800 to 1900, or rather during the 19th century, the land mass controlled by Europe increased, and it increased by a lot. The land mass in North America and South America came to be totally controlled by the Europeans. There were more and more colonies in the African continent, where multiple European nations managed to get hold onto some piece of it. Also, South and Southeast Asia were mostly controlled by European nations, and the Pacific islands and small parts of East Asia fell under their control too.