अक्षरांच्या मालिकेतल्या (?) चा जागा भरून टाका : AC, DG, HL, ?, SY, ..............

The first letters A, D, H, ?, S advance by 3, 4, 5, 6, so the missing one is M. In each pair the second letter is 2, 3, 4, 5, 6 places ahead of the first (A→C, D→G, H→L, M→R, S→Y). The term is MR.