Which of the following do not require a medium for transmission?

An electromagnetic wave in vacuum has the electric and magnetic field $\vec{E}$ and $\vec{B}$,which are always perpendicular to each other. The direction of polarization is given by $\vec{X}$ and that of wave propagation by $\vec{k}$. Then:

An electromagnetic wave with frequency $\omega$ and wavelength $\lambda$ travels in the $+y$ direction. Its magnetic field is along the $+x$ axis. The vector equation for the associated electric field (of amplitude $E_0$) is:

Consider the following:
$I.$ Waves created on the surfaces of a water pond by a vibrating source.
$II.$ Wave created by an oscillating electric field in air.
$III.$ Sound waves travelling under water.
Which of these can be polarized?

The magnetic field in a plane electromagnetic wave is given as $B = (3 \times 10^{-7} \text{ T}) \sin (3 \times 10^4 x + 9 \times 10^{12} t) \hat{j}$. The electric field of this wave is given as:

If $E_{o}$ and $B_{o}$ are the magnitudes of the electric and magnetic fields respectively of an electromagnetic wave in vacuum,then among the following the correct relation is ($\mu_0-$ permeability of free space,$\varepsilon_0-$ permittivity of free space).