Which of the Following Is True Regarding Agarose Gel Electrophoresis

Which of the following is true regarding agarose gel electrophoresis of DNA?

A) The loading dye usually contains a marker dye and a heavy molecule such as glycerol.
B) In general, good separation of DNA fragments in the 1000-20,000 base pair size range can be achieved.
C) The usual buffer used is potassium phosphate at a pH of 7.2.
D) The usual stain to visualize the DNA is propidium iodide.