The correct answer is: C. been done
The sentence “This work ought to have been done long ago” is in the past perfect passive voice. The past perfect passive voice is used to talk about something that should have been done or happened before a certain time in the past. In this case, the work should have been done before the present time.
The other options are incorrect because they are not in the past perfect passive voice. Option A, “done,” is in the simple past tense. Option B, “had done,” is in the past perfect tense, but it is in the active voice, not the passive voice. Option D, “being done,” is in the present progressive tense.
Here is a diagram that shows the different verb tenses and voices:
Tense | Active | Passive
——- | ——– | ——–
Present | I do | I am done
Past | I did | I was done
Future | I will do | I will be done
Present perfect | I have done | I have been done
Past perfect | I had done | I had been done
Future perfect | I will have done | I will have been done
I hope this explanation is helpful!