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'.
Actually, the superlative form of "bonita" wouldn't be "bonitísima", it would merely be "muy bonita". Just like "very beautiful", not "beautifullest"
You use the verb ser to describe the date, origin, characteristics, time, occupation, and relationships. You use the verb estar to describe location and feelings.
Answer:
yeah be safe their 675000 are death their this is so sad
