Which is not proportionate to 15/45
3/9
3/15
1/3
30/90

You would reduce each of them down by dividing both the top and bottom by the same number, so 15/45 turns into 1/3
3/9 - 1/3
3/15 - 1/5
1/3
30/90 - 1/3
The only one that's different is 3/15

The first answer is correct