Answer:
6 and 6
Explanation:
All elements have an equal number of protons and neutrons
Estuaries are areas where fresh water from rivers meets salt water. As the river drains, it carries much nutrient-rich sediment. Many animal species depend on this food source to provide for their young.
I believe its A. I may be wrong.
The question is asking the determine the role that the United States do in the ecosystem base on the passage and situation in the question that you have state, base on my research, I would say that its role is a Dominant. I hope you are satisfied with my answer and feel free to ask for more if you have question and further clarification