Study the following gene cloning vector and identify the correct statements.

I. Cloning sites are absent in ori region 
II. ${\mathrm{tet}}^{\mathrm{R}}$has restriction site for BamH I and Sal I
III. It is reconstructed cloning vector 
IV. It has two marker genes. 

Cloning sites should be absent at the ori site because if gene is inserted at ori site, DNA replication is prevented. The marker ${\mathrm{tet}}^{\mathrm{R}}$ has cloning sites BamH I and Sal I. It has two marker genes such as ${\mathrm{amp}}^{\mathrm{R}}$ and ${\mathrm{tet}}^{\mathrm{R}}$. It is a reconstructed vector because it is constructed from three plasmid sources. They are pSC101 from which $te{t}^R$ is obtained, Ori gene is obtained from Col E plasmid and ampicillin resistance gene is obtained from Col ${\mathrm{E}}_1$ plasmid.