Final answer:
The correct verb form in this sentence is 'llegó' in the preterite (pretérito) tense.
Step-by-step explanation:
The verb form that is correct in this sentence is llegó. The sentence is in the past tense, so the correct verb form should be in the preterite (pretérito) tense, which expresses completed actions in the past. Here, 'el camarero llegó en seguida' indicates that the waiter arrived immediately, which is a specific action that happened once in the past.
Learn more about Verb forms in Spanish