Modelo
You hear: Estudio para el examen.
You select: la biblioteca

ancient india is often called the harappan civilization because one of the ancient cities was called harappa. harappa was just one of 1500 cities in the indus river valley. another well-known city is called mohenjo-daro. historians estimate ancient india to be the biggest of all four early civilizations.

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