The correct verb pair to complete the sentence is 'coman, beban.'
The correct verb pair that completes the sentence is option A: 'coman, beban.'
When using the subjunctive mood after 'no creo que' (I don't believe that), the correct verb forms are 'coman' for the plural 'personas' (they eat) and 'beban' for the plural 'personas' (they drink).
For example, the sentence would read 'No creo que muchas personas coman de forma saludable durante las fiestas' (I don't believe that many people eat healthily during the holidays).