Which of These Factors Allows the Bouncing of Sand Grains

Which of these factors allows the bouncing of sand grains to exceed 0.5 m in height (off the ground) during saltation?

A) Particle size. Very fine and fine-grained sand may bounce as high as 2 m, after hitting other sand particles in saltation.
B) Lower density. Weathered platy minerals (clays and micas, primarily) are lofted further off the ground.
C) Bouncing off of bedrock instead of off of other sand or silt grains.
D) Air pressure. Extremely low air pressure (as occurs near or within tropical storms and depressions) can allow sand clasts to bounce as much as 2 m in height before being pulled back downward.