Final answer:
The correct verb form to complete the sentence is 'tienen'.
Step-by-step explanation:
The correct verb form to complete the sentence is tienen.
The sentence is saying 'they are hungry if they don't eat now.' The subject 'ellas' is the third person plural form for 'they.' The verb form 'tienen' is the present tense form of the verb 'tener' which means 'to have.' So the correct sentence in English would be 'They are hungry if they don't eat now.'
Here is an example to illustrate:
Ellas tienen hambre si no comen ahora.
(They are hungry if they don't eat now.)
Learn more about Spanish verb conjugation