Hematologic system questions

When whole blood is run through a centrifuge, why does plasma separate to the top of the tube, while red blood cells separate to the bottom?

(Choice A)
The red cell fraction occupies a greater volume than the plasma fraction
(Choice B)
The red cell fraction has a greater mass than the plasma fraction
(Choice C)
The components of the red cell fraction are larger than the components of the plasma fraction
(Choice D)
The red cell fraction has a greater density than the plasma fraction

MCAT