How is a literary device used to develop the tone in the stanza below?

Excerpt from Elizabeth Bishop’s poem “The Fish”
his brown skin hung in strips

like ancient wallpaper,

and its pattern of darker brown

was like wallpaper:

shapes like full-blown roses

stained and lost through age.

a. A fearful tone is developed through the use of symbolism
b. A happy tone is developed through the use of imagery
c. A mysterious tone is developed through the use of onomatopoeia
d. A tone of wonder and awe is developed through the use of imagery (my answer)

d. A tone of wonder and awe is developed through the use of imagery