The correct answer is option (2)- B Transformed cells
Origin of replication (ori) is a sequence from where replication starts and any piece of DNA when linked to this sequence can be made to replicate within the host cells. In addition to ‘ori’, the vector requires a selectable marker, which helps in identifying and eliminating non- transformants and selectively permitting the growth of the transformants. Transformation is a procedure through which a piece of DNA is introduced in a host bacterium (you will study the process in subsequent section). Normally, the genes encoding resistance to antibiotics such as ampicillin, chloramphenicol, tetracycline or kanamycin, etc., are considered useful selectable markers for E. coli. The normal E. coli cells do not carry resistance against any of these antibiotics. So, an antibiotic resistance gene in a vector usually helps in the selection of transformed cells.