The direction of magnetic field at a point on the magnetic lines of force can be taken along:

Explanation

The correct answer is Option C. The direction of the magnetic field at a point on magnetic lines of force is along the tangent to the field line at that point. This is because magnetic field lines represent the path along which a north pole would move, and at any given point, this motion is tangential to the curve of the field line.Option A is incorrect because the normal to a point is perpendicular to the field line and does not indicate the direction of the magnetic field.Option B is incorrect because the axis of the magnetic line of force is a conceptual line and does not necessarily indicate the direction of the magnetic field at every point.Option D is incorrect because the magnetic field within a solenoid is parallel to its axis, not perpendicular.