In this excerpt from emily dickinson's poem "dying," what is the meaning of the word onset?

i heard a fly buzz—when i died—
the stillness in the room
was like the stillness in the air—
between the heaves of storm—

the eyes around—had wrung them dry—
and breaths were gathering firm
for that last onset—when the king
be witnessed—in the room—

a. arrival
b. beginning
c. creation
d. emergence

b b b b b b   b b b   b b b b b

the answer is a because the astrophel does more and sidney goes to the astrophel more than stella.

c. "but thy eternal summer shall not fade" (line 9)

1. the relationship between a pronoun and its antecedent- reference

reference refers to the relationship between mainly pronoun and another unit of grammar- noun phrase or noun.

2. a singular noun naming a collection or group- collective noun.

collective noun refers to the kind of noun which refer to the name of people, thing or anything in collective. for instance bundle of sticks, herein 'bundle' is collective noun.  

3. a modifying clause whose subject and/or verb is implied- elliptical clause

it is a clause in which words are being left out. on the other hand, the missing word is understood due to the logic or pattern of the sentence.  

4. two or more nouns and/or pronouns serving the same grammatical function and followed by a pronoun that references one or all nouns- compound antecedent

compound antecedent refers to which is made up of two or more words which are joined by 'or' or 'and.'

5. an adjective clause introduced by a pronoun- relative clause.

relative clauses are the clauses which begin with the relative pronouns such as when, where, which, that or who. the noun that precedes, relative pronouns identify or define that noun.  

6. the word, phrase, or clause to which a pronoun refers- antecedent.

antecedents refers to the phrases, clauses or words which are replaced with one of the third personal pronouns.