B. entered / was playing / had been playing / had done
Feedback 1. We use the Past Simple for short completed actions in the past: entered the room. 2. We use the Past Continuous for interrupted actions which were in progress in the past - was playing the guitar. 3. We use the Past perfect Continuous to emphasize the duration of some action in the past - had been playing all evening. 4. We use here the Past Perfect to emphasize the result - had done nothing