Pneumococcal resistance to penicillin G is mainly acquired by  :
Acquisition of antibiotic resistance by Transduction is common in Staphylococcal and that of by Transformation in Pneumococcus and Neisseria.
Vancomycin resistance in enterococci and Staphylococcus is mediated by the conjugative plasmid.
Conjugation
Transduction
Transformation
All of the above