The Past Continuous tense is used to describe an action that was in progress at a particular point in the past. This contrasts with Simple Past, which describes a completed action in the past. * **Core Concept:** Understanding different past tenses. * **Solution Analysis:** Option C is the direct way of expressing ongoing past action. * **Detailed Option Analysis:** * **A:** Incorrect. Simple past expresses completed actions. * **B:** Incorrect. Present perfect connects the past with present. * **C:** Correct. Past Continuous indicates an ongoing past action. * **D:** Incorrect. Future Simple is about future events. * **Common Mistakes:** Mixing up Simple Past and Past Continuous tenses.