Answer:
The correct answer is D. Immigration is when animals move into an ecosystem.
Explanation:
Animal migration is the movement of animals from one habitat to another, caused by specific needs for food, hibernation, climatic issues, or even to escape predators. Migration, like the migration of birds, is a directed migration, that is, it aims at a specific end; while dispersion is the more or less random distribution of a group of individuals over the habitat. Thus, within the migratory process of animals, two movements are distinguished: emigration, which is the departure of animals from a place, and immigration, which is the entry or arrival of these to the new habitat.
Sedimentary rocks are 'built up' over time, and if something dies overtime, lets say an animal, it will get buried and minerals will fill it and it becomes a fossil. fossils are important because they tell us about the past and what is was like way back when.
Answer:
I'm not 100% sure but I'm positive the answer was or is Methane, correct me if I'm wrong!