In somatic hybridization, protoplasts of two different cells are fused by using ___________.

The correct option is D Polythylene glycol
Somatic hybridization is a technique to obtain hybrid plants with desired characters by the fusion of protoplasts of two varieties or species. The plant cells lacking cell wall are called protoplasts.

Protoplast fusion between the protoplasts of the selected parents is induced by a solution of polyethylene glycol (PEG) or by high voltage electric current. PEG is a fusogen which disrupt the phospholipid bilayer resulting in the fusion of protoplasts. The fusion of protoplast involves the fusion of both cytoplasm and nuclei.

Figure : Protoplast fusion

Sodium bicarbonate, hydrogen chloride, calcium chloride do not serve any purpose in fusion of protoplasm.