The correct option is C Gene transfer without a vector
Polyethylene glycol method is used for gene transfer without a vector. Introduction of DNA into plant cell without the involvement of a biological agent and leading to stable transformation is known as direct gene transfer. There are various methods for direct gene transfer one of which is chemical method. Certain chemicals e.g. PEG polyethylene Glycol, polyvinyl alcohol and calcium phosphate enhance the uptake of DNA by plant protoplast. PEG and calcium phosphate are thought to precipitate the DNA onto the outer surface of plasmalemma and the precipitate is taken up by the endocytosis.
So, the correct option is option B.