Volatility of diesel fuel oil is

• A. It catches fire without external aid
• B. Temperature at which it solidifies or congeals
• C. Minimum temperature to which oil is heated in order to give off inflammable vapours in sufficient quantity to ignite momentarily when brought in contact with a flame
• D. Indicated by 90% distillation temperature, i.e., when 90% of sample oil has distilled off

Answer: (D)