Step 1: Context.
Polythene, when burnt, gives off toxic fumes with a pungent smell.
Step 2: Option Analysis.
(A) ghee: Gives a pleasant smell.
(B) polythene: Correct — Known for pungent, harmful smoke.
(C) life: Irrelevant.
(D) oil: Smell is different, not pungent in this sense.
Step 3: Conclusion.
Correct answer is (B) polythene.