Select the option that will correctly come in the place of question mark to complete the below number series.

6, 11, 19, 30, ?, 61, 81

Logic: Double difference of the series is 3. →(5, 8, 11, 14, 17, 20) 

6 + 5 = 11

11 + 8 = 19

19 + 11 = 30

30 + 14 = 44

44 + 17 = 61

61 + 20 = 81

So, the missing number is 44.

Thus, the correct option is  (d) 44