Our Environment

In the following groups of materials, which group (s) contains only non-biodegradable items?
(i) Wood, paper, leather
(ii) Polythene, detergent, PVC
(iii) Plastic, detergent, grass
(iv) Plastic, bakelite, DDT
(a) (iii)                                   (b) (iv)                  (c) (i) and (iii)        (d) (ii) and (iv)