Final answer:
The correct verb form is 'comen'.
Step-by-step explanation:
The correct verb form to complete the sentence is comen. The subject, 'Ellas', is the third-person plural pronoun in Spanish, so we use the verb form 'comen', which also indicates a plural action. The other verb forms, 'come' and 'comemos', do not match the subject of the sentence.
Learn more about Verb forms in Spanish