Final answer:
The correct verb is 'Hay' which means 'there is/are' in Spanish.
Step-by-step explanation:
The correct verb to complete the sentence is Hay. The sentence should be 'Hay muchas personas en la tienda.'
'Hay' is the third person singular form of the verb 'haber' which means 'to have' or 'there is/are' in Spanish. In this context, it indicates the existence of many people in the store.
For example, if you were describing a crowded store, you could say 'Hay muchas personas en la tienda' to express that there are many people there.
Learn more about Spanish verbs