Multiple choice Directions: Complete the series. AB : BD : : AC : ? BC BD BE AB BF Reveal answer Fill a bubble to check yourself E Correct answer Explanation Taking the positions of letters A = 1, B = 2 and so on. Multiplying the combination by 2, 12 * 2 = 24 = BD Similarly, AC = 13 Multiplying it by 2, we get 13 * 2 = 26 = BF.