Aditya added L-2 drops of iodine to three test tubes A, B and C, containing 2 ml of food samples. A dark blue-black colour appeared in test tubes A and B. The correct order of food samples taken in test tubes A, B and C is:

(a) rice, dal, potato

(b) rice, potato, dal

(c) potato, dal, rice

(d) dal, rice, potato