According to the context, the possessive adjective to complete the conversation is "mi" and the correct substantive is "tia".
What are substantives?
It is a kind of word that can function as the subject of a sentence and that designates to name an object, subject, place, concept.
In the sentence "Ella es la hermana de mi madre. Es mi tia Gloria", "mi" is a possessive adjective that modifies the substantive, in this case "tía" is a feminine substantive that refers to her mother's sister.
Therefore, we can conclude that according to the context, the possessive adjective to complete the conversation is "mi" and the correct substantive is "tia".
Learn more about Spanish substantives here: https://brainly.com/question/21736962
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