Safe Bike For Teenager

So, it's my nephew's birthday soon, I am gonna to buy a scooter for himself. Any advices on choosing a safe bike for teenager?

If you want safe, get him a bike with 4 wheels, and doors.

Bike, as in Bicycle, or a scooter, as in something powered?
As for bicycle, consider something that has off road capabilities. They are less prone to road terrain problem of a road bicycle with skinny tires.

I mean scooter. So, now I'm choosing between tvs jupiter and new honda. First thing looks better for me, but my nephew asks me to buy activa 5g. I don't know what to do... In my opinion, this scooter looks more like a motorcycle! It can be dangerous for 15-years-old boy. It's a good choise for adult, not teenager. Athough, exterior is brilliant, young people like it...