The most important feature in a plasmid to serve as a vector in gene cloning experiment is:

The correct option is D Origin of replication (ori)
Features of an ideal vector:

Presence of an origin of replication (ori), a selectable marker, sites for the action of restriction endonucleases and small size are important features of an ideal vector.

Origin of replication:

The most important feature in a plasmid to serve as a vector in gene cloning experiment is the presence of an origin of replication or ori site. Origin of replication allows the plasmid to self replicate without being dependent on genomic DNA replication.

Role of a selectable marker:

Selectable marker helps in identifying and eliminating non-transformants and selectively permitting the growth of transformants.

Cloning sites:

Cloning sites (recognition sites) are the sites of the vector where the DNA is cut by a restriction endonuclease for incorporation of the gene of interest.

Size:

The ideal size of a cloning vector should be less as the chances of breakage of DNA increases during the purification process.

Final answer :

a. Origin of replication (ori)