Proteins are removed by treatment with

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:

Study the given figure carefully and select the correct statements regarding this.
$I.$ It represents typical agarose gel electrophoresis showing differential migration of $DNA$ fragments.
$II.$ Lane $1$ contains undigested $DNA$ fragments.
$III.$ Lanes $2$ to $4$ contain digested $DNA$ fragments.
$IV.$ Smallest $DNA$ bands are present at $(A)$ position and largest $DNA$ bands are present at $(B)$ position.

Consider the following statements about $PCR$:
$I.$ Polymerase Chain Reaction $(PCR)$ is a technique of synthesizing multiple copies of the desired gene in vitro.
$II.$ This technique was developed by Kary Mullis in $1985$.
$III.$ $A$ single $PCR$ amplification cycle involves three basic steps: denaturation,annealing,and extension.
Which of the statements given above are correct?

During the processing of the prohormone $proinsulin$ into the mature $insulin$—

Which technique is used to check the progression of a restriction enzyme digestion?