Answer :

(a)

i) ‘A; Circular DNA/Plasmid ‘B’ Bacteriophage

ii) (Plasmid)-Can carry foreign gene into the host cell/acts as cloning vector/has selectable marker/ independent of the control of chromosomal DNA/ high copy number. (Bacteriophage) -Cloning vector have the ability to replicate in bacterial cells / independent of the control of chromosomal DNA / high copy number per cell.

or

(b) Treating bacteria with specific concentration of calcium (ions) which increases the efficiency with which DNA enters the bacteria through pores in its cell wall ,recombinant DNA can then be forced into such cells by incubating the cells with recombinant DNA on ice, followed by placing them briefly at 42°C (heat shock), then putting them back on ice.