Which enzyme is responsible for the replication of recombinant $DNA$ in the host?

Select the correct statement from the following.

Given below are two statements.
Statement $I$ - The isolated $DNA$ of donor organism is cleaved by suitable restriction endonuclease to form $DNA$ fragments with cohesive staggered or blunt ends.
Statement $II$ - The foreign $DNA$ or passenger $DNA$ can also be obtained directly from genomic or cDNA library.
In the light of above statements,select the correct option given below:

Separation and purification by filtration,centrifugation of the desired compound produced in a bioreactor is a part of:

Which of the following should be chosen for best yield if one has to produce a recombinant protein or enzyme on a large scale,using microbial,plant,animal,or human cells?

It increases the efficiency with which $DNA$ enters the bacterium through pores in its cell wall.