Option (1) is the correct answer because separated DNA fragments can be visualised only after staining the DNA with a compound known as ethidium bromide followed by exposure to UV radiation. We cannot see pure DNA fragments in visible light and without staining. ⇒ The DNA fragments separate (resolve) according to their size through sieving effect provided by agarose gel. ⇒ DNA is a negatively charged molecule, hence it moves towards the positive electrode (anode).