¿era mariela la chica de la casa blanca? no, mariela no estaba la chica de la casa blanca. no, mariela no eras la chica de la casa blanca. no, mariela no era la chica de la casa blanca. no, mariela no eres la chica de la casa blanca.

The person that asks the question wants to know if Mariela was the girl in the white house. The answer is a negation because it uses the word no, which is an expression that means we use to contradict some or all of the meaning of a positive sentence. On the other hand, this is the correct answer because the word era is the conjugation of the verb ser for the third person singular in the imperfect, which is the case of the response.

maria est visitando la argentina.