Final answer:
The correct possessive adjective to fill in the blank is 'su'.
Step-by-step explanation:
The correct possessive adjective to fill in the blank is su.
The sentence 'Este sombrero es de usted. Es su sombrero, ¿verdad?' translates to 'This hat is yours. It is your hat, right?'
'Su' is used to indicate possession with singular nouns, regardless of gender. It is commonly used to show ownership or possession by a single person.
Learn more about Possessive Adjectives