If you throw a rock into a pond, it creates a wave in the water. what is responsible for creating an electromagnetic wave? hints

surface wave of water is due to the disturbance of medium particles

this is also known as mechanical waves

In mechanical waves we need a mechanical medium to disturb the medium particles which will produce the disturbance

While electromagnetic waves do not require any medium and it can propagate through vacuum

Electromagnetic waves are propagation of electric and magnetic field which is due to oscillation of charge.

So electromagnetic field requires to and from motion of charge particle in which time dependent electric field will induce magnetic field and then they induce each other and propagate in the medium