Which line of this excerpt from "Ozymandias" by Percy Shelley reflects the theme that art alone can last forever?

Explanation:

"Ozymandias" is a poem by Percy Shelley. It talks about the foolish desire of the Eygptian King Ramesses who built  a statue of himself in the bid to immortalize himself.

The statue was broken and the face that was left depicted the king's expressions and emotions. These expressions and emotions will be after his death; even after his death, his expressions has been inscripted on the statue.

Therefore, the line "nothing beside remains round the decay" simply says,  "that art alone can last forever" which gives the insight that even after king dies and his life gone and decayed,  the statue as an art will still live on.

demonstrative is te word i think