Final answer:
The correct verb form to complete the sentence is 'coman'.
Step-by-step explanation:
The correct verb form to complete the sentence is coman. In this sentence, the phrase 'Es importante que ustedes' indicates that the subject is 'ustedes' (you all). When talking about a recommendation, advice, or suggestion in Spanish, we use the subjunctive mood. The subjunctive form of the verb 'comer' (to eat) in the third person plural is 'coman'.
Learn more about Spanish verb conjugation