To tell someone what you just have done, you should use ‘acabo de bailar’. The word ‘acabo’ in this sentence means ‘I just danced’. The other sentences are in different tenses.
‘Estoy bailando’ is in the present form, it means you are dancing now. ‘Hace tres días que bailo’ means you are still dancing now and you started three days ago. And ‘Hace tres días que bailé’ means you danced three days ago.
Estoy bailando means I am dancing Hace tres días que bailo means I danced three days ago Hace tres días que bailé means It's been three days since i danced Acobo de bailar means I have just danced so the answer is Acobo de bailar
