Select the restriction endonuclease enzymes whose restriction sites are present for the tetracycline resistance (tet ${ }^R$ ) gene in the pBR322 cloning vector.

The correct answer is option (1), because the restriction sites for restriction endonucleases Bam HI and Sal I are present within the tet ${ }^R$ gene in the pBR322 cloning vector. Options (2), (3) and (4) are incorrect because the restriction sites of $P$ st I and $P v u I$ are present within the $a m p^R$ gene in the pBR322 cloning vector.