Answer: Option (A) is the correct answer.
Step-by-step explanation:
Kerosene is made up of a mixture of water, oil, rocks and some contaminants that are extracted from porous layers of carbonate rock and sandstone.
Kerosene has lowest flash point, that is, lowest temperature at which a substance can vaporize in the air to form an ignitable mixture.
Therefore, due to this reason when kerosene comes in contact with slightest of flame then it immediately catches fire and becomes explosive in nature.
Hence, we can conclude that when Lionel is replacing the kerosene in a heater then he should avoid flames.