Which of the following injuries can be life threatening? head injuries neck injuries back injuries all of the above

All of them can be very life threatening

All of the above.
If you hit your head, you can suffer severe trauma, concussion, or even death.
If you suffer from neck injuries, you can end up dying as there is where your veins carry oxygen to your brain.
If you injure your back, you can damage your spinal cord which will prevent you from moving.If you can't move, you're preventing natural mechanism (such as eating and going to the bathroom) to take place. You need to eat and use the bathroom to keep your body running