Answer:
This is basically a learning disorder where an individual's capability of understanding spoken as well as written language. Person's with this disorder can not understand what the other person is saying to him or her, they can't figure it out properly and in some cases those person even can't get the writings. Many researchers have tried finding out it's cause what they are not sure about it but they have given some possible causes like, transferred from family, having very less interaction with people etc.
For example, it you say go and receive pizza at the door, the person suffering with this disease will not figure it out what instructions he or she has got.
Peak and top because crest means the top of mountain or hill
