I know that he did the work- বাক্যটির সঠিক পরিবর্তিত voice কি হবে?

অপশনসমূহ
সঠিক উত্তর চিহ্নিত
ক It was known to me that the work has been done by him.
খ It was known to me that the work had been done by him.
গ It was known to me that the work was done by him.
ঘ It is known to me that the work was done by him.