Final answer:
The correct form of the verb in the sentence is 'tenía'.
Step-by-step explanation:
The correct form of the verb in the sentence is 'tenía'. The imperfect form of the verb 'tener' ('to have') in the third person singular is 'tenía'. So the correct sentence would be 'El panadero tenía que hacer pan en la noche.'
Learn more about Imperfect verb form in Spanish