Answer:
A. thought that silence is golden.
Step-by-step explanation:
In this passage from Story of Echo and Narcissus, Echo faces the sentence of not being able to speak because of her constant talking and saying last word in conversations. The goddess Juno did not over talkative habit of Echo. Since it is a Greek myth, and myths represent the concerned culture's values, we can infer from this that Ancient Greek thought that silence is golden.
In Greek myth "Echo and Narcissus" is a tragic story of Echo and Narcissus. It is also found in Ovid's book of poetry (Metamorphoses). Echo is a nymph which annoys Juno (Hera) by detaining her by her talk when she (Juno) was searching for her husband who was amusing himself with the nymphs. When Juno discovers this, she passes sentence upon Echo that she will not be able to talk/speak, but she will only be able to utter last word of someone else's speech. The story next describes about Narcissus's indifference to Echo only because of her inability to speak. And later Narcissus too (unknowingly) falls in love of his own reflection in the story. The bodies of both Echo and Narcissus dissolve because of not finding the love from their beloved ones.
The options B and C are not relevant to this passage, nor to this story. Option D is totally incorrect because they did believe in their myths.