Magnetic field lines provide a convenient way to visualize a magnetic field. Which of the following statements is not true?
a. The path followed by an iron particle released near a magnet corresponds to a field line.
b. The path followed by an electric charge released near a
magnet corresponds to a field line.
c. A compass needle in a magnetic field turns until it is
parallel to the field lines around it.
d. Magnetic field lines do not actually exist.