Ans. (a) Nodular sclerosis(Ref: Robbins 9th/pg 606-611)Binucleated owl shaped nuclei with clear vacuolated area refers to Lacunar cells.Lacunar cells are seen in the nodular sclerosis subtype of Hodgkin's diseaseLacunar cells have delicate, folded, or multilobate nuclei and abundant pale cytoplasm that is often disrupted during the cutting of sections, leaving the nucleus sitting in an empty space (lacuna)