In the following groups of materials, which group/groups contain only non-biodegradable materials?
wood, paper, leather
polythene, detergent, PVC
plastic, detergent, grass
plastic, bakelite, DDT
(a) (iii) (b) (iv) (c) (i) and (iii) (d) (ii) and (iv)

Correct answer: (d) (ii) and (iv)

Explanation: polythene, detergent, PVC, plastic, bakelite, and DDT materials cannot be degraded by micro-organisms and hence are non-biodegradable.