Excuse me, what's the difference between A c options? Can you explain "being done something" in detail?

Done is the perfect tense of do; What should be done has been done, it has been done; What is being done is in progress, which means that it is being done; The present perfect tense indicates completion/completion. To is just a conjunction and a guide.

Be do emphasizes that it is going on and cannot be used as an adverbial of purpose.