S is the surface of a lump of magnetic material.

Options

A. Lines of B are necessarily continous across S
B. Some lines of B must be discontinous across S
C. Lines of H are necessarily continous across S
D. Lines of H cannot all be continous across S

Explanation

Magnetic field lines for magnetic induction (B) form continous lines. So, lines of B are necessarily continous across S.
Also, magnetic intensity (H) varies for inside and outside the lump. So, lines of H cannot all be continous across S.