Right answer: Eat!
¡Coma! Is the imperative form of the verb comer (to eat) for the third person in singular él/ella/eso/esa (he/she/it) and for the second person (formal) in singular usted (you).
In Spanish grammar the Imperative is used by the speaker to give orders, advice or make requests to one or more people directly. It is also used to exhort, incite or send another person to do something.
Note the forms of imperative in Spanish exist for all the personal pronouns except the first person in singular Yo (I).
In addition, note that for its conjugation the imperative is written without the personal pronoun and in present tense. This is why “Eat!” is written with no subject.