KeerthanaPosted on 3, 9, 21, 45, ? a93 b87 c54 d78 Answer : Option AExplanation : 3 × 2 + 3 = 9 9 × 2 + 3 = 21 21 × 2 + 3 = 45 Rate This:NaN / 5 - 1 votesAdd comment