Can someone plss help me I don't understand this!

What is the best meaning for obscure in this line from the passage? a) ancient b) dark c) royal d) unknown

That time of year thou mayst in me behold when yellow leaves, or none, or few do hang upon those boughs which shake against the cold, bare ruined choirs, where late the sweet birds sang in me thou sees the twilight of such day as after sunset fadeth in the west; which by and by black night doth take away, death's second self that seals up all in rest. in me thou seest the glowing of such fire that on the ashes of his youth doth lie, as the deathbed whereon it must expire, consumed with that which it was nourished by. this thou perceiv'st, which makes thy love more strong, to love that well, which thou must leave ere long. the first stanza compares the leafless limbs of a tree to a. yellow leaves b. sweet birds c. bare choirs d. summer

What is articulating thoughts and ideas effectively using oral written and non-verbal skills a part of