¿cuál es el mejor complemento para la siguiente oración? los trenes de costa rica corrían cuando de repente a) había un terremoto b) hubo un terremoto c) hay un terremoto

The correct option to choose is:

Explanation:

With all those three steps now you can choose the answer. In this case is letter b) hubo un terremoto

corras is the only one that is informal but doesn't follow the suffix rule. correr is the verb. corre is the formal verb form. corra would be used as the formal is corre ended with an a.

your best bet would be corras, it's the only one that is informal but is still wrong