The correct answer is had been depressed. Key Points The correct structure to be used: had been + verb in the past participle. This is used to indicate that the action began in the past and continued up to a given time in the past. Let us see an example to understand: I had been worried about you. Where were you all these days? Important Points In the given sentence, the depression began in the past and he continued to be depressed for a period of time. That explains the use of ‘had been + verb’ structure. Now, the verb should be in the past participle. So, depressed is the correct form. His friends claimed that he had been depressed for a few months. Therefore, the correct answer is option 2.