Observations, surveys, and models.
1.D 2.A that is pretty hard
It’s c I believe because it says 209 years to complete an orbit so hint yourself ?.....
Answer:
Erosion is the washing away of the uppermost part of the earth crust. Once erosion starts it only gets worse because, erosion wash away further soil, causing the eroding channel to futher expand, increasing the erosion.
Lack of vegetative cover allows erosion which washes away soil nutrients, further worsening the soil against soil vegetative cover.
