What is the effect of high temperature $(94^{\circ}C)$ on $DNA$?

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:

During the process of isolation of $DNA$,chilled ethanol is added to

Gel electrophoresis is used for

Proteins are removed by treatment with

What does 'competent' refer to in competent cells used in transformation experiments?