It allows the reader to decide what type of personality a character has without being told by the author. This can encourage the reader to pay closer attention to what a character is doing and saying in order to figure out what type of person he or she is.
B.
It tells the reader what type of person a character is so that the reader doesn't have to figure it out based on how the character acts and reacts.
C.
It encourages the author to use powerful adjectives to describe the character's personality at length.
D.
It is the only way in which an author is able to use figurative language to fully describe a character and the setting within a scene.