Multiple choice Norwegian scientists have determined Rudolph's nose is red because ... They couldn't figure it out, so they say it's magic. Duh. He was actually born that way; it's a birthmark. It's a parasitic infection of his respiratory system. Santa fed him a special diet of only red foods. Reveal answer Fill a bubble to check yourself C Correct answer Explanation A tongue-in-cheek study by researchers in Norway suggested that Rudolph's nose is red due to a parasitic infection of his respiratory system, which causes high blood flow to the area. This is a humorous scientific take on the myth.