Density is a physical property that describes the relationship between mass and volume. Density is the amount of matter in a given space, or volume.
An arrow pointing from the bottom of the ramp to the top, I assume it would be friction.
Answer: D. meter, kilometer
SI or "International System of Unit" is the unit that used in the international organization to make counting easier.
In this case, all of the options are base SI but if you compare them both they are a different unit that can't be converted each other. You can't convert gram into second.
Only option D. meter, kilometer is had the same unit that can be converted.
