Task: Question Answering
Input (English): Background Paragraph: The body's second line of defense against pathogens includes the inflammatory response. If bacteria enter the skin through a scrape, the area may become red, warm, and painful. These are signs of inflammation. Inflammation is one way the body reacts to infections or injuries. Inflammation is caused by chemicals that are released when skin or other tissues are damaged. The chemicals cause nearby blood vessels to dilate, or expand. This increases blood flow to the damaged area, which makes the area red and slightly warm. The chemicals also attract white blood cells called neutrophils to the wound and cause them to leak out of blood vessels into the damaged tissue. 
Story: Ryan is carrying groceries from his car back to his apartment when he trips and falls landing on his knees. Embarrassed, he gets back up, picks up his groceries and carries them into his apartment with his head down. After putting his groceries away, he notices that although both of his knees are scraped, only his left knee is warm to the touch. His right knee feels cool when he puts his hand on it. 
Question: Which of Ryan's knees doesn't have bacteria in it?
Output (English): right knee.