14.Calvin, a 14-year-old boy frequently wakes in the morning with clear recollection of very frightening dreams. Once he awakens, he is normally alert and oriented, but the dreams are a persistent source of distress. His mother reports that he sometimes murmurs or groans but does not talk or move during the period before awakening. His history is otherwise notable for having been homeless and living with his mother in a series of temporary shelter accommodations for 1 year when he was 10 years old. What is the most likely diagnosis