Which of the following statements are correct with respect to DNA separation, isolation and visualization ?
A. The cutting of DNA is done by molecular scissors.
B. The DNA fragments separate according to their size in an agarose gel, upon electrophoresis.
C. The separated DNA fragments can be seen without staining when exposed to UV light.
D. The separated DNA fragments, when stained with ethidium bromide, can be seen in visible light.
Choose the correct answer from the options given below :

(B) A and B only
Statement A is correct. Restriction endonucleases are commonly referred to as molecular scissors because they cut DNA molecules at specific recognition sites.
Statement B is correct. During gel electrophoresis, DNA fragments are separated based on their size through the sieving effect of the agarose gel. Smaller fragments move farther and faster than larger ones.
Statement C is incorrect. Separated DNA fragments cannot be seen without staining. They must be stained with a specific dye, such as ethidium bromide, to be visualized.
Statement D is incorrect. Even after staining with ethidium bromide, DNA fragments cannot be seen under visible light. They must be exposed to ultraviolet (UV) light, under which they appear as bright orange bands.
Therefore, only statements A and B are correct.