Cloning vectors in genetic engineering: A plasmid is considered a suitable cloning vector when which set of properties is satisfied?

Introduction / Context:
In molecular cloning, the choice of vector determines how efficiently foreign DNA can be inserted, propagated, and recovered. Plasmids are popular cloning vectors because they are small, circular DNA molecules that replicate independently of the bacterial chromosome. This question tests the core design features that make a plasmid an effective vector in a teaching or research laboratory.

Given Data / Assumptions:

• The goal is to insert, maintain, and recover a foreign DNA fragment in a bacterial host.
• Typical operations include restriction digestion, ligation, transformation, selection, and plasmid purification.
• Stable replication and ease of handling are essential.

Concept / Approach:
Good vectors combine practical lab handling with genetic features: a selectable marker, a well-characterized origin of replication, and a multiple cloning site containing unique restriction sites. Additionally, insertion of DNA should not abolish plasmid replication; the replication origin and copy-number control elements must remain intact regardless of the insert.

Step-by-Step Solution:

Verification / Alternative check:
Standard plasmids (for example, pBR322-derivatives, pUC-series) are widely used because they satisfy all these properties and have robust documentation and protocols.

Why Other Options Are Wrong:

Common Pitfalls:
Inserting DNA into essential vector loci (ori, marker) or using vectors with duplicated restriction sites that produce unwanted fragmenting during cloning.

Final Answer:
All of the above.