What aspect of nature does the star represent in the poem?

bright star
by john keats

bright star, would i were stedfast as thou art--
not in lone splendour hung aloft the night
and watching, with eternal lids apart,
like nature's patient, sleepless eremite,
the moving waters at their priestlike task
of pure ablution round earth's human shores,
or gazing on the new soft-fallen mask
of snow upon the mountains and the moors--
no—yet still stedfast, still unchangeable,
pillow'd upon my fair love's ripening breast,
to feel for ever its soft fall and swell,
awake for ever in a sweet unrest,
still, still to hear her tender-taken breath,
and so live ever—or else swoon to death.

a. its vastness as it looks down upon the mountains, as if they were mere actors wearing masks
b. its spiritual importance as the overseer of all of earth, cleansing life of its impurities
c. its indifference toward the trivial details that constitute human life on earth
d. its constancy in contrast to the rapid changes the speaker undergoes
e. its difference from the speaker's love, who unfortunately will not live forever