Fillers are words that are part of spoken language but do not contain any meanings. These are usually referred to as unnecessary pauses in speaking such as using the words uhm, uh or er. The best way to avoid using filler words is to plan carefully so that you don't lose your train of thought.
Explanation: From what I can remember from the story, the son of the man trying to escape warmed him not to fly so high and from his own pride, he fell. Also none of the other answers make sense because they relate to the story and questions like these should be based solely on a main idea or topic, the central focus.