I think the correct answer is receptor. To respond to a chemical signal a cell must have a receptor and also this where the signaling molecule can bind. A receptor is a protein molecule that can receive signals from the outside environment of the cell.
The answer is D) desertification and deforestation
To know the answer you can rule out the non-possibilities. A is not correct because farmers use them all the time. B is not correct because water and pesticides can flow downstream and carry and deposit sediment. C is not correct because farmers can flood their own farms. When they plant things and a food comes, all of those plants will die or their roots will detach which lowers the food that can be sold. D is correct because farmers don't farm in the desert or the forest, so it would not be an impact of farming.
They are called paleontologists.
Answer: divergent boundary where crust plates are.
Explanation: The Mid-Atlantic Ridge is a mid-ocean ridge, a divergent or constructive plate boundary located along the floor of the Atlantic Ocean, and part of the longest mountain range in the world.