Una vez me rompí el brazo. Tuve que ir al hospital. me operaron y el doctor lo arregló
The answer is B. estudiante.
The article preceding it, 'las', is the plural feminine article. 'estudiante' in the sentence is singular only, but it is gender neutral. 'son' is the third person plural conjugation of the verb 'ser'. 'inteligentes' is an adjective that would refer to plural subjects. To fix the sentence, change 'estudiante' to 'estudiantes'.
Solo por un rato , it could be nos vemos en el restaurante , but I would choose A
