Neha took a burning candle and covered it with an empty glass by putting it upside down. She observed that the candle burns for some time before it finally goes off. What is the reason for this?

• A.  The candle keeps burning for some time as long as the air present in the glass is available to it and then it goes off.
• B.  The ignition temperature of the candle becomes low due to glass cover hence it goes off.
• C.  The candle keeps burning as long as the complete wax melts away and then goes off.
• D.  Oxygen is produced when the candle burns. This oxygen keeps the candle burning for some time and then it goes off.