The answer is: A. greater density.
Density of distilled water is 1 g/mL.
Density of sea water is greater than distilled water and is approximately 1.022 g/mL (d(sea water) = 1.022 g/mL).
Less dense object floats on more dence substances.
Density of a substance is its mass per unit volume.
The SI derived unit for density is the kilogram/cubic meter, but chemist usually use gram per cubic centimeter.