The correct answer is - b. destructive.
Once the mountains stop their lifting up and also the other features are done with their formation, the erosion process takes over and starts to do its work by slowly wearing down the mountains and other features. The tendency of the erosion process is to flatten everything that it affects, so if there isn't any significant change that will cause lifting up of the terrain, the erosion will be able to flatten the space as much as possible. The erosive processes are considered as destructive processes because they are destroying the land features.
Q2. Indians and Africans were considered black. Some Americans were even considered black too.
Yes, imperialism exists in the modern age. They are not exactly the same as the ones we read in our textbooks, but they do still exist in modern age. An example is Cultural imperialism. Where America influences others through the internet such as social media, music, brands, moves etc.
The correct answer is number two