Answer:
la conozco
Explanation:
Ana, ¿conoces a la maestra de historia?
Sí, yo la conozco
Translation:
Ana, do you know the history teacher?
Yes, I know her
In the first place we discard the option "la se" since in Spanish the use of the verb "saber" with respect to this sentence would not make sense. Then the gender is determined, in this case we are talking about the history teacher, therefore it belongs to the third person of the singular "la".
