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.
Around 1800 (plus or minus about 5 years) is when it was estimated that the world's population had reached 1 billion.
Answer: not eating enough food, because cells need molecules from both food and air to work
Explanation: the air and food are creating energy for the organism
