The following four particles A, B, C, and D are of equal volume and are dropped into a column filled with water. Particle A is flat with a density of 2.5 grams per cubic centimeter. Particle B is flat with a density of 3.0 grams per cubic centimeter. Particle C is round with a density of 2.5 grams per cubic centimeter, and particle D is round with a density of 3.0 grams per cubic centimeter. Which particle would usually settle most rapidly?
PARTICLE D