Which of the following statements are correct?
(A) Electric monopoles do not exist whereas magnetic monopoles exist.
(B) Magnetic field lines due to a solenoid at its ends and outside cannot be completely straight and confined.
(C) Magnetic field lines are completely confined within a toroid.
(D) Magnetic field lines inside a bar magnet are not parallel.
(E) $\chi =-1$ is the condition for a perfect diamagnetic material, where $\chi$ is its magnetic susceptibility.

Choose the correct answer from the options given below :

Magnetic materials used for making permanent magnets $\left(\mathrm{P}\right)$ and magnets in a transformer $\left(\mathrm{T}\right)$ have different properties of the following, which property best matches for the type of magnet required?

The figure shows a region of length '$\mathcal{l}$' with a uniform magnetic field of  $0.3 \mathrm{T}$ in it and a proton entering the region with velocity $4\times {10}^5 \mathrm{m} {\mathrm{s}}^{-1}$ making an angle $60°$ with the field. If the proton completes $10$ revolution by the time it cross the region shown, '$\mathcal{l}$' is close to (mass of proton $= 1.67\times {10}^{-27} \mathrm{kg}$, charge of the proton$= 1.6\times {10}^{-19} \mathrm{C}$)