Answer:
<u>1</u><u>)</u><u>Amplitude</u>
<u>2</u><u>)</u><u>Modulation</u>
<u>3</u><u>)</u><u>Frequency</u><u> </u>
<u>4</u><u>)</u><u>Modulation</u>
It believe the answer is the second choice, "have a subject and a verb."
Independent clauses are complete sentences, which knocks out the third and fourth option.
Dependent clauses are not complete thoughts, knocking out the first option.