Read the excerpt from Dr. Martin Luther King Jr's "I Have a Dream" speech. [1] I am happy to join with you today in what will go down in history as the greatest demonstration for freedom in the history of our nation.

[2] Five score years ago, a great American, in whose symbolic shadow we stand today, signed the Emancipation Proclamation. This momentous decree came as a great beacon light of hope to millions of Negro slaves who had been seared in the flames of withering injustice. It came as a joyous daybreak to end the long night of their CAPTIVITY.

[3] But one hundred years later, the Negro still is not free; one hundred years later, the life of the Negro is still sadly crippled by the manacles of segregation and the chains of discrimination; one hundred years later, the Negro lives on a lonely island of poverty in the midst of a vast ocean of material prosperity; one hundred years later, the Negro is still languished in the corners of American society and finds himself in exile in his own land.

Which phrase from the text provides the best context clue to determine the meaning of "captivity" in paragraph 2?

a
Joyous daybreak

b
One hundred years

c
Still not free

d
Sadly crippled

i think its c but b is also another choice c or b

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.