In the following question, a related pair of word or phrase is followed by a pair of words or phrase. Select the pair that best expresses a relationship similar to the one expressed in the original pair.
Dulcet refers to sweet and soothing sound often used ironically. Raucous refers to, making or constituting a disturbingly harsh and loud noise. So the relationship is here completely opposite to each other.
Therefore the option is correct as crazy and insane are synonymous.