For the first passage, the most closely matching meaning of the word "countenance" is:
D. noun | facial expression
In this context, "countenance" refers to the facial expression of the raven, contributing to the overall mood of the scene.
For the second passage, the central theme of the passage is:
A. The narrator attempts to distract himself from his grief through reading.
The narrator expresses a longing to escape his sorrow through reading, which emphasizes the theme of attempting to cope with grief.