Gel Electrophoresis Is a Useful Tool in DNA Cloning

Gel electrophoresis is a useful tool in DNA cloning. At a neutral pH, when voltage is applied, DNA fragments will migrate toward the anode because:

A) DNA is negatively charged due to its glycine backbone.
B) DNA is negatively charged due to its phosphate backbone.
C) DNA is positively charged due to its glycine backbone.
D) DNA is positively charged due to its phosphate backbone.