I would say D) Geology. That's a whole other subject itself. Economics, geography, and history all fit into the category Social Studies. That is things happening around the world. Social stuff. Hence the name Social Studies. So once again, D is your answer. Geology is about the science that deals with the earth's physical structure and substance, its history, and the processes that act on it. The geological features of an area. That would not fit in.
~Silver