Which of the following statements are true for magnetic field lines?
a. At every point in space, the magnetic field vector at that point is tangent to the magnetic field line through that point.
b. Magnetic field lines are close together in regions of space where the magnitude of the magnetic field is weak, and they are father apart in regions where it is strong.
c. Unlike electric field lines, magnetic field lines are continuous.
d. Magnetic field lines point in the direction of the magnetic force acting on a charge. e. Magnetic field lines can never intersect.