Answer:
C. The word "ghosts" is used to represent Robert's haunting
memories.
Step-by-step explanation:
Robert in the passage is obviously a victim of PTSD. Describing the emotional and psychological baggage that many war veterans carry as a 'ghost' is a poignant metaphor that gives the passage its haunting tone.
The significance here is that even though the ghosts are not real or are remnant memories of things long past they can affect and haunt one's present if one believes in them. thus it is a good metaphor to show Robert's condition.