Identify the function of plasmid DNA.

To confer certain unique phenotypic characters to bacteria

The correct answer is Option (3) – To confer certain unique phenotypic characters to bacteria

The function of plasmid DNA is to confer certain unique phenotypic characters to bacteria. Plasmids are small, circular DNA molecules that are separate from the bacterial chromosome. They often carry genes that provide bacteria with specific advantages, such as antibiotic resistance or the ability to metabolize certain nutrients. Plasmids can replicate independently within the bacterial cell and can be transferred between bacteria through processes like conjugation, allowing the spread of these advantageous traits. Therefore, plasmid DNA plays a crucial role in bacterial adaptation and evolution.