The correct answer is 34

The first thing you should do is to discover the pattern and progression of the series. To do this it, its helpful to write the working numbers for your solution. Please look at the example below:

The numbers increase, so addition or multiplication are involved.

1     4     10     16     19     25     31     ?

  +3    +4     +6    +3    +6     +6     +3 = 34