In the following question, select the missing number from the given series.
86, 107, 82, 111, 78, 115, ?

Correct option is D

Given: 86, 107, 82, 111, 78, 115, ?
Series 1 (1st, 3rd, 5th terms): 86, 82, 78
The logic here is subtracting 4 from the previous number:
86 → 82 (86 - 4)
82 → 78 (82 - 4)
Following the pattern, the next number in this series will be:
78 - 4 = 74
Series 2 (2nd, 4th, 6th terms): 107, 111, 115
The logic here is adding 4 to the previous number:
107 → 111 (107 + 4)
111 → 115 (111 + 4)
Conclusion:
The missing number in the sequence is 74.
The correct option is (d) 74.