Select the number from among the given options that can replace the question mark (?) in the following series.
139 136 131 124 115 ? 91

139, 136, 131, 124, 115, ?, 91

Logic: The differences are increasing by 2: 3, 5, 7, 9, 11, 13,...

139 - 3 = 136
​136 - 5 = 131
​131 - 7 = 124
​124 - 9 = 115

Similarly,
​115 - 11 = 104

104 - 13 = 91

Thus, the correct option is (c).