The question is about verb tenses. The Past Continuous tense is used to describe an action that was happening at a specific moment in the past. The Present Perfect tense refers to an action that has happened at an unspecified time in the past or that has a result in the present. The Future Perfect tense is used for an action that will be completed before a certain point in the future. The Past Simple tense is used for an action that happened at a specific time in the past, but it does not necessarily imply the action was ongoing. Therefore, the Past Continuous is the most accurate answer.