Which pair of verbs best completes this sentence?
ayer, mi prima se de la bicicleta y se la pierna.

cortó, quemó

golpeó, lastimó

cayó, rompió

lastimó, quemó

Both words are conjugations of different verbs but in the same tense. So this tense is the preterite. 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 cayó comes from the verb caer and rompió comes from the verb romper. Both conjugations stands for the third person singular. On the other hand, this sentence uses the reflexive pronoun se (third person singular). In Spanish, we use Reflexive Pronouns with a verb to point out that a person carries out an action to or for himself or herself. Finally:

Ayer, mi prima se cayó de la bicicleta y se rompió la pierna