Final answer:
The correct answer is 'A. fuertes' which means strong in Spanish.
Step-by-step explanation:
¡Hola! The correct answer to fill in the blank is A. fuertes, which means strong. The sentence translates to: My older brothers are not weak; they are very strong. In this context, the word fuertes describes the physical strength of the brothers.
Learn more about The meaning of the word 'fuertes' in Spanish