Final answer:
The correct form of the verb estar (to be) is ellos están.
Step-by-step explanation:
The correct form of the verb estar (to be) is ellos están. In Spanish, the verb estar is used to express the state of being or location. It is conjugated differently depending on the subject pronoun. In this case, the subject pronoun is ellos, which means 'they'. Therefore, the correct form is están.
Learn more about Spanish verb conjugation