The possessive form is the protesters' opinion.
The possessive phrase would be "the teacher's book."
The singular possessive form for the noun opinion is opinion's.Example: My opinion's foundation is a lot of research.
The possessive noun phrase is the fathers' rights.
The possessive noun phrase is the fathers' rights.
There is no possessive noun unless you change the phrase to read, 'the children's telephone'. In this example the possessive noun is children's.
The possessive form is the visitors' lounge.
The possessive form is the friends' committee.
The possessive form of the plural noun fathers is: the fathers' rights.
The possessive noun phrase is: his paw's dirty prints
"The ant colony's" is not a sentence, it's a noun phrase. There is no possessive pronoun in this noun phrase. There is no pronoun in this noun phrase.
The possessive phrase are the man's shoes.
The possessive form is Ron's dance.