Which of the following statement is not correct about cloning vector?

(a) ‘Ori’ is a sequence responsible for controlling the copy number of the linked DNA.

(b) Selectable marker selectively permitting the growth of the non-transformants.

(c) In order to link the alien DNA, the vector needs to have single recognition site for the commonly used restriction enzymes.

(d) The ligation of alien DNA is carried out at a restriction site present in one of the two antibiotic resistance genes.