Which of the following group of organisms are not constituents of a food chain? (i) grass, lion, rabbit, wolf (ii) plankton, man, fish, grasshopper (iii) wolf, grass, snake, tiger (iv) frog, snake, eagle, grass, grasshopper (a) (i) and (iii) (b) (iii) and (iv) (c) (ii) and (iii) (d) (i) and (iv)