It's not a denotation. If it were, the earth would be cinder long forgotten millions of years ago.
It really isn't to reveal the importance of watching the sky. The word burn is used poetically. If the poem wanted you to watch the skies, it would have said so either directly or indirectly using poetic language. Nowhere are you being asked to watch the skies.
There is nothing in theory about the burn and as a consequence there is nothing critical in the tone.
That only leaves A but it is not a very good answer.
A <<<< answer.
Nature is raw and tangible, which often helps characters find who they really are when they are lost in the wilds.
Examples:
-siddhartha: the ferry man found that the river was an allegory for life
-where the red fern grows: billy found his true belonging (of being a leader) when he was outside in nature with his dogs
It is true that the expressionist described the world outside the character through the character's moods and impressions.
Human where monkey before and go play game bruh jost become pro gamer and you will have a lot of money you don’t have to work a day