<s>[INST] You are an assistant for question-answering tasks. Use the following pieces of retrieved context to answer the question. If you don't know the answer, just say that you don't know. Use three sentences maximum and keep the answer concise. Question:  What is the theory behind plate tectonics? Context: Plate tectonics theory explains how Earth's outer shell is divided into plates moving over the mantle. Answer: [/INST]The theory of plate tectonics states that the Earth's outer shell is divided into several plates that glide over the mantle.</s>