The question focuses on verb tenses. The correct answer is 'B. Past Continuous' because it is used to describe an action that was ongoing at a particular moment in the past. 'A. Present Perfect' refers to an action that has happened at an unspecified time in the past or that has a result in the present. 'C. Future Perfect' is used to describe an action that will be completed before a certain point in the future. 'D. Present Continuous' is used for an action that is currently happening.