Read the excerpt below and answer the question. but time drives flocks from field to fold; when rivers rage and rocks grow cold; and philomel becometh dumb; the rest complains of cares to come. (“the nymph’s reply to the shepherd”; lines 5-8) which uses an auditory (sound) appeal to support the idea that natural landscapes are not idealized settings? a“… drives flocks from field to fold; ” b“… rocks grow cold; ” c“… cares to come.” d“philomel becometh dumb; ”

The answer is D) “Philomel becometh dumb". 
Two key pieces of information are needed to correctly answer the question: 
1) Remember that "dumb" also means, and long ago more commonly meant, unable to speak, or mute.
2) Philomel is a princess in Greek Mythology who is raped by her sister's husband and is transformed to a nightingale, a songbird whose song is generally seen as sorrowful. 

Philomel becoming dumb means the princess, transformed into a nightingale, has lost her ability to fill the air with her sorrowful song, her one expression of sadness that she has. This is what makes it an auditory appeal. 

It has the potential to lead to limits on rights by giving flexibility in making laws.

This answer would be c