Pronouns refer to the words which replace the noun and eliminated the repetition of words.
Possessive pronouns refer to the pronouns which highlight ownership or possession in a sentence.
The antecedent for the possessive pronoun refers to the pronoun or noun to whom it shows the possession.
Therefore, in the above sentence, the case of the underlined pronoun as well as the antecedent to which it refers is possessive; Miriam as 'freestyle round' is the performed by her.