Which of the following enhances or induces fusion of protoplasts?

The high molecular weight polymer (1000-6000) of PEG acts as a molecular bridges connecting the protoplasts. Calcium ions linked the negatively charged PEG and membrane surface. When PEG elute, the surface potential are disturbed, leading to intramembrane contact and subsequent fusion due to the strong affinity of PEG for water which may cause local dehydration of the membrane and increase fluidity, thus inducing fusion.