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: Two medical school students named Dan and Bob learned about the human immune system. Dan studied more about the subject, and became very interested to pursue it more in the future. 
Question: Which student didn't learn that the infected skin area may become painful?
Output (English): Bob.