Find the missing number in the following series.
4, 7, 12, (…), 28, 39

Correct option is A

Given - 4, 7, 12, (…), 28, 39
7 - 4 = 3
12 - 7 = 5
difference may be odd numbers starting by 3 so next difference should be 7
12 + 7 = 19
19 + 9 = 28 which satisfied with next term so
final answer is 19.

alternative method: