In the screening process during rDNA experiments, clones that metabolize $\beta$-gal turn:

1. Colorless

2. Blue

3. Yellow

4. Green

How are transformants selected from nontransformants?

1. Presence of more than one recognition site in the vector DNA.

2. Presence of alien DNA into the vector DNA results into insertional inactivation of selectable marker.

3. Antibiotic resistance gene gets inactivated due to insertion of alien DNA.

4. Both 2 and 3.

Insertional inactivation of a gene helps in
a. Identification of recombinant clones
b. Identification of deletion mutants
c. Identification of recombinant transformants
d. Elimination of suppression mutants

Insertional inactivation of the lac Z gene forms-

Which of the following would you choose as the safest and least cumbersome selectable marker-