Answer:
A. The waves are making a lapping sound as they hit the beach and pull out into the ocean.
Step-by-step explanation:
The waves lapping refers to the act of the waves hitting or splashing against anything that is on their way. The waves come and hit the shores and then retreat back to the vast ocean. This to and fro movement of the waves is called 'lapping'.
Likewise, the phrase "waves lapping" when used in the given sentence refers to the sound that the waves make when they hit the beach and retreat into the ocean.
Thus, the correct answer is option A.