Final answer:
The appropriate verb form to fill in the blank in the dialogue is 'está'. In Spanish, the verb 'estar' is used to express feelings or states of being.
Step-by-step explanation:
The appropriate verb form to fill in the blank in the dialogue is está.
The dialogue is asking 'How are you, teacher?'. In Spanish, the verb 'estar' is used to express feelings or states of being. Since 'profesora' is a formal address, the appropriate verb form is 'está', which means 'are'.
Learn more about Verb forms in Spanish