Electrophoresis is a technique in which DNA fragments migrate through an agarose gel using an electric current. Since DNA is negatively charged by phosphate groups, it will move toward the positive pole. And the distance traveled will depend on the number of base pairs in the fragment. For example, a fragment with 100 base pairs will move less distance than a fragment with 10 base pairs because it is heavier.
Therefore the order of the fragments from smallest to largest would be as follows:
1- B
2- C
3- D
4- A
