Final answer:
The appropriate preterite form of the verb sentirse to fill in the blank is 'se sintieron' and it indicates a completed action in the past.
Step-by-step explanation:
The appropriate preterite form of the verb sentirse to fill in the blank in the sentence 'Gerardo y yo. muy contentos después de la reunión' is option A: se sintieron.
The preterite tense is used to talk about completed actions in the past. In this sentence, Gerardo and I felt very happy after the meeting, indicating a past action that has already been completed.
For example, if you translate the sentence in English, it would be 'Gerardo and I felt very happy after the meeting', emphasizing the completed action in the past tense.
Learn more about Preterite tense in Spanish