Final answer:
The most appropriate verb to fill in the blank is 'estoy' which means 'am'.
Step-by-step explanation:
Yo estoy barriendo el piso.
The most appropriate verb to fill in the blank is 'estoy'. In Spanish, the verb 'estar' is used to describe actions that are happening at the moment. Since the sentence states 'Yo' which means 'I' in English, the verb form 'estoy' is the correct choice.
For example: 'Yo estoy barriendo el piso' translates to 'I am sweeping the floor' in English.
Learn more about Spanish verbs