What vibrates in the following types of wave (I) light waves (Ii) sound waves (III) x-ray (iv) water waves?

(I) Light waves - Electromagnetic fields vibrate in light waves.
(II) Sound waves - Air particles vibrate in sound waves.
(III) X-ray - X-ray waves are a type of electromagnetic radiation, so electromagnetic fields vibrate in x-ray waves.
(IV) Water waves - Water molecules vibrate in water waves.

(I) Light waves: electric and magnetic fields
(Ii) Sound waves: air molecules
(III) X-rays: photons
(iv) Water waves: water molecules

What is parabola