When $DNA$ fragments are stained with ethidium bromide and viewed under $UV$ light,what color do they appear?

Refer to the following statements for agarose-gel electrophoresis:
$(a)$ The $\text{DNA}$ fragments resolve according to their size.
$(b)$ The separated $\text{DNA}$ fragment can be visualised only after staining with ethidium bromide followed by exposure to $UV$ radiation.
$(c)$ $\text{DNA}$ is always loaded into the well.
$(d)$ The smallest fragment of $\text{DNA}$ is near the well.
Choose the correct statements:

Which of the following range of temperature is required for denaturation,annealing of primer,and primer extension of $PCR$ respectively?

In the above represented plasmid,an alien piece of $\text{DNA}$ is inserted at the $\text{EcoRI}$ site. Which of the following strategies will be chosen to select the recombinant colonies?

The technique used to make numerous copies of a specific segment of $DNA$ quickly and accurately is

The preparatory phase before fermentation is known as: