Final answer:
The winged odor was repelled by the beauty of the palace.
Step-by-step explanation:
The most likely explanation for the winged odor being kept away in the second stanza of Roderick Usher's poem is option d. Something unpleasant was repelled by the beauty of the palace.
In the last two lines of the stanza, it is stated that 'A winged odor went away.' The use of the word 'went away' suggests that the odor was repelled or driven out by something. Since the earlier lines describe the ramparts of the palace as 'plumed and pallid', it can be inferred that the beauty of the palace repelled the unpleasant odor.
This interpretation aligns with the theme of the poem, which explores the contrast between beauty and decay, and the power of art to triumph over darkness and despair.