<em>Answer:</em>
<u><em>D</em></u>
<u><em /></u>
<u><em>Explanation:</em></u>
<u><em>Hertz is the SI unit used for frequency, and it is defined as one wavelenght per second in physics. Considering that waves repeat themselves in cycles, D is a reasonable answer</em></u>
<u><em /></u>
<u><em /></u>
Maybe you should try to rub it with acetone?
