The diagram shows the result when a student placed a magnet under a piece of paper, then sprinkled iron shavings on the paper. The iron shavings are distrubuted this way because magnets....

a. have magnetic fields that flow from one pole of the magnet to the other.
b. have multiple magnetic fields that attract the shavings with different strengths.
c. have magnetic fields that repel magnetic materials and push the shavings away.
d. have uneven magnetic fields that attract the shavings in random patterns.