Read the following passage carefully:

pBR322 DNA is a commonly used plasmid cloning vector in E. coli. Created in 1977 in the laboratory of Herbert Boyer at the University of California. The molecule is a double-stranded circle 4,361* base pairs in length.  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. This sequence is also responsible for controlling the copy number of the linked DNA can be made to replicate within the host cells . The cloning vector pBR322 contains selectable markers ampicillin and tetracycline resistance genes. Ampicillin gene sequence is provided with restriction sites PVU-I &PST-I. Tetracycline gene sequence provided with Bam HI &Sal I . They play a supportive role in the differentiation of transformed cells from non-transformed cells. They also aid in distinguishing between recombinant and non-recombinant cells. In order to link the alien DNA, the vector needs to have very few, preferably single, recognition sites for the commonly used restriction enzymes. Presence of more than one recognition sites within the vector will generate several fragments, which will complicate the gene cloning.

Attempt the following questions based on the passage:

Which of the following is not a desirable feature of a cloning vector?