Based on the options provided, the most probable answer to this question is increase. The landmass that was controlled by Europe from 1800 to 1900s increased. Thank you for your question. Please don't hesitate to ask in Brainly your queries.
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.
Landslides are frequently triggered by strong ground motions(Earthquakes). They are an important secondary earthquake hazard. Slope material that becomes saturated with water may develop a debris flow or mud flow. which can effect the slums
