Which of the following produces electromagnetic waves?

If $\varepsilon_0$ denotes the permittivity of free space and $\phi_{E}$ is the flux of the electric field through the area bounded by the closed surface,then the dimensions of $\left(\varepsilon_0 \frac{d \phi_{E}}{dt}\right)$ are that of

$A$ variable frequency $AC$ source is connected to a capacitor. How will the displacement current change with a decrease in frequency?

How are electromagnetic waves produced?

Give the equation that relates the speed of light $c$,the permeability of free space ${\mu _0}$,and the permittivity of free space ${\epsilon _0}$.

The source of a time-varying magnetic field may be:
$(A)$ A permanent magnet
$(B)$ An electric field changing linearly with time
$(C)$ Direct current
$(D)$ A decelerating charged particle
$(E)$ An antenna fed with a digital signal
Choose the correct answer from the options given below: