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'.
"What works of art or literature influence your life "
Hay Una Grande Fiesta Para El Cumpleaños De Mi Abuelo.
Carolina: Mi amigo Ramón __es__ de Guatemala y ahora __está__trabajando en los Estados Unidos.
Option C