Correct Answer - A
Transformation is permanent heritable change in a cell, particularly a bacterial cell, that occurs as a result of its acquiring foreign DNA. But cells normally do not take up foreign DNA molecule because DNA is a hydrophilic macromolecule and its movement through lipid membrane is opposed. special methods such as `CaCI_(2)` treatment, electroporation, particle delivary method, etc, are used to make host cells competent i.e., able to take up foreign DNA.
