My first F30 problem.

Ok so just out of the blue cruising on the highway the other day the car now has a slight humming noise like a wheel bearing as soon as you go over 100km/h. Its on its loudest at about from 120km/h. You can only hear it clearly on smooth tar roads. I have tried to figure out what side by changing lanes sharply at 120 but it stays the same. I have even switched to neutral but it stays the same.

I can only rule these options
1 wheel bearing
2 gearbox
3 diff
Any other F30 drivers experience a similar problem