Gauss's Law For Magnetism

NCERT Class 12, Chapter 5 (Magnetism and Matter) states Gauss's law for magnetism: the net magnetic flux through any closed surface is zero, written $\oint \vec{B}\cdot d\vec{A}=0$. Physically this means magnetic field lines always form closed loops, with no starting or ending points, because there are no isolated magnetic charges (monopoles). Every field line that enters a closed surface must also leave it, so the inward and outward contributions cancel exactly. The option 'field lines can begin on charges' describes electric fields and Gauss's law for electricity, not magnetism. The option 'the field is always non-uniform' is unrelated to flux and is untrue in general. The option 'magnetic forces do no work' is a true but separate fact about the Lorentz force, not the cause of zero flux. Plausibility check: for electric fields the flux equals enclosed charge over ${\epsilon }_0$; the magnetic analogue is zero precisely because the magnetic 'charge' (monopole) has never been observed, confirming the first option.