ANSWER: Janice's observation that is explained by Hypothesis I but not by Hypothesis II is that shortly after the candle was covered by the glass beaker, the flame diminished and soon went out.
REASONING:
Hypothesis I mentions oxygen as an important part of the chemical reaction that causes certain objects to burn. By placing the glass beaker over the candle, the oxygen supply is cut off. Once the oxygen inside the beaker is consumed, the flame diminishes and goes out.
Hypothesis II does not mention oxygen as an important part of the chemical reaction.