500
Four kids were assigned to take notes on a light bulb. Each person either had a Prediction, Question, Hypothesis, or Observation. The "1" Kid said, "Do light bulbs light up on their own?" Kid "2" said, "If I have a light bulb, then it will light up." Kid "3" said, "I noticed that light bulbs light up sometimes." Kid "4" said, "If light bulbs light up, then dark bulbs will light up." Kid "_" was chosen to give a sentence about an observation.
What is 3?