Is there any more to this question? Like a passage/short text that would explain?
If there is, the question is asking ‘The captain was the happiest’ which then you would need to use context clues pulled from whatever article there was.
This sentence is given in the imperfect tense. This tense is used to talk about past actions, conditions, or events that occurred regularly or frequently or that were in progress in a moment in the past. Here we use the verb ser conjugated as era that stands for the third person singular. Also, this sentence stands for superlatives. The superlative is a form of an adjective that expresses the highest possible amount of something talking about what is <em>the most </em>or <em>the least</em>. So:
