<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 function of red blood cells in the body? Context: Red blood cells transport oxygen from the lungs to the body's tissues and carbon dioxide back to the lungs. Answer: [/INST]The main function of red blood cells is to transport oxygen from the lungs to the body's tissues and carbon dioxide back to the lungs.</s>