Final answer:
The appropriate preterite verb to fill in the blank in the sentence is "se enojó".
Step-by-step explanation:
The appropriate preterite verb to fill in the blank in the sentence "Mi hermano __ mucho conmigo porque rompí su guitarra" is se enojó. The verb "enojó" is in the preterite tense, which is used to indicate a completed action in the past. In this case, it expresses that the brother got very angry with the speaker because they broke his guitar.
Learn more about preterite verb usage in Spanish