What is the criteria for DNA fragments movement on agarose gel during gel electrophoresis ?

Smaller the fragment size, the farther it moves.

The correct answer is Option (3) - Smaller the fragment size, the farther it moves.

During gel electrophoresis, DNA fragments separate based on their size and charge. The gel, typically made of agarose, acts as a molecular sieve that slows down the movement of DNA fragments as they migrate through the gel under the influence of an electric field.

When an electric field is applied, the negatively charged DNA fragments move towards the positively charged anode. Smaller DNA fragments can move through the gel more easily and thus migrate faster towards the anode compared to larger fragments. The DNA fragments separate (resolve) according to their size through sieving effect provided by the agarose gel. Hence, the smaller the fragment size, the farther it moves.