¿quiénes iban a la fiesta? gladys ibamos a la fiesta. felipe ibas a la fiesta. patricia y felisa iban a la fiesta. varinia ibaste a la fiesta.

The correct conjugation of the verb "ir" in Imperfect Tense, taking into account the noun used, is:

Patricia y Felisa iban a la fiesta.

Translation.

Patricia and Felisa were going to the party.

Imperfect Tense in Spanish.

The Imperfect form of the verb "ir," taking into account the personal pronouns, is:

Yo: ibaTú: ibasUsted: ibaÉl: ibaElla: ibaEllo: ibaNosotros / Nosotras: íbamosUstedes: ibanEllos / Ellas: iban

Since the nouns Patricia and Felisa can be replaced by the personal pronoun "ellas," the conjugation "iban" used in the answer is the correct one, therefore, the correct option is "Patricia y Felisa iban a la fiesta."

More information:

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Quien iban a la fiesta ? 

ir (preterito imperfecto)
iba ivas 
iba 
ibamos
ibais
iban

nosotros ibamos
tu ibas
Patricia y Felisa (ellos) iban a la fiesta  = correct
! Baste ! por Ibasteno sé con el ! in the other side ...I don't know !!

hope I helped !!

Incorrecto así no se dice

The answer is b because it’s los amigos . los amigos is plural and dicen is plural and masculine .