Which word from the poem best summarizes the overall mood of the poem?

Read the passage from Ozymandias.

And on the pedestal these words appear:
“My name is Ozymandias, king of kings;
Look on my works, ye Mighty, and despair!”
Nothing beside remains. Round the decay
Of that colossal wreck, boundless and bare
The lone and level sands stretch far away.

Which word from the poem best summarizes the overall mood of the poem?

a. king
b. despair
c. decay
d. colossal