¿qué hizo el caballo? el caballo corrió rápidamente. el caballo corrí rápidamente. el caballo corrimos rápidamente. el caballo corriste rápidamente.

Caballo is the animal that we name in English horse. This is the correct answer because corrió is the correct conjugation in this sentence. So corrió is the conjugation of the verb correr for the third person singular in the simple present. Recall that the preterite tense is one of two simple past tenses. It is used to describe actions that took place or were completed at a certain point in the past. So The horse ran quickly. Finally:

El caballo corrió rápidamente

answer might be "si", would be better if you added answer choices