The question below refer to the selection "where have you gone, charming billy? ": an element of the story that is least related to the author’s biographical story is the…
a. geography of the vietnamese coastline.
b. fear that soldiers feel during wartime.
c. smell of mildew in a vietnamese village.
d. vivid description of the climate and landscape in.

I think that the element of the story that is least related tot he author's biographical story is the C. SMELL OF MILDEW IN A VIETNAMESE VILLAGE.

Tim O'brien wrote the story using his personal experiences. He was sent to Vietnam in his tour of duty. He's familiar with the geography of the Vietnamese coastline, he vividly describes the climate and landscape, and he feels the fear that the soldier felt during wartime.