Two successive discounts on an article are given to a customer. Find the second discount. (I) The first discount is 20%. (II) The marked price of the article is Rs 600. (III) The selling price of the article is Rs 400.

Successive discounts problem. First discount is 20% on MP of Rs 600, reducing it to Rs 480. Final SP is Rs 400, so second discount is (480-400)/480 = 16.67%. Statements I (20% first discount) and III (SP=Rs 400) are sufficient with MP given in II. But careful: MP is in statement II. So I and III alone are NOT sufficient - we need MP from II. Therefore I, II, and III together are sufficient. Option E 'None of these' would mean the correct combination is not listed. Let me verify: if the answer is E, it implies none of A-D are correct. A is 'Only II & III' - insufficient without discount %. B is 'Only I & II' - insufficient without SP. C is 'Only I & III' - insufficient without MP. D says all three together are NOT sufficient - but they ARE sufficient. So E is correct - the right answer (all three together) isn't listed in A-D.