We use here the properties of magnetic field lines which state that the no. of magnetic field lines enters in closed surface is equal to the no. of magnetic field lines comes out to the surface.So, flux linked with a closed surface is always zero. option \(A\) is correct another property is, magnetic field lines are always \(\perp\) to surface from where they start and where they end. option \(B\) is not correct also magnetic field lines pass through conductor always. option \(C\) is not correct and hence,The correct opt: \(A\)