B. Senator Akunin. ~I can't submit it unless it's 20 characters long so ignore this entire sentence~
Answer:
But, my mouth was a sandy desert.
Explanation:
Not sure if there is another metaphor? is this the whole paragraph?
Lightheartedness means cheerful, carefree ect.
This means the line "The sounds of water splashing and laughter echoed in the distance; Tim's friend's had gone for a late-night swim." is the phrase that is the correct answer, since it talks about the happy actions of Tim's friends.
Answer C.