Final answer:
The imperfect form of the verb 'ser' (to be) in the sentence 'El capitán era el más feliz' is correct.
Step-by-step explanation:
The imperfect form of the verb in the sentence 'El capitán era el más feliz' is correct.
In Spanish, the imperfect tense is used to describe ongoing or repeated actions in the past. It is often used to set the scene or provide background information. In this sentence, 'era' is the imperfect form of the verb 'ser' (to be) and is correctly used to describe a characteristic of the captain in the past.
For example: El capitán era el más feliz de todo el equipo. (The captain was the happiest on the whole team.)
Learn more about Spanish verb conjugation