The so-called "Dark Romantics" notwithstanding, the best answer would be
C. Innocence
William Blake, although considered a "Pre-Romantic," wrote a book of poetry entitled, "Songs of Innocence and of Experience" -- in which he wrote
"Piping down the valleys wild Piping songs of pleasant glee On a cloud I saw a child. And he laughing said to me.
Pipe a song about a Lamb; So I piped with merry chear, Piper pipe that song again— So I piped, he wept to hear.<span> </span>
...And I wrote my happy songs Every child may joy to hear"
This typifies Romanticism, in that the child, like the "Noble Savage"-indigenous peoples in pre-industrializing areas of the 18th- and-19th-centuries, remains in an effectively "unspoiled" state of being.
The open window and the landlady both show the creepy experience by the main character. Both add to the experience with imagery and (should I continue?)