The criteria for disorders in DSM-5 are structured so that someone either has or does not have a given disorder. This is known as diagnosis.

the correct answer is a

answer; conventional stage;

i believe the answer is: true

our brain need to reach a certain level of development   before it could interpret and understood sound with high difficulties. to proof this, we just need to pay attention in musical preference between children and adults. it is far less likely that children would enjoy things such as orchestra or rock band as much as adults due to the difference in this ability.