In the following groups of materials, which group/groups contain only non-biodegradable materials ?
(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)