Answer:
The answer is Bob
Explanation:
The science exist to kinds of measurements base units and derive units of measurement.
Base units are the ones that measure: length, mass, time, electric current, temperature, luminous intensity and amount of substance.
Derivative units of measurement are obtain when we combine the base units.
Know from your question
Bob measures length is a base unit
Jill measures density is a derivative unit, is the combination of mass and volumen
Kim measures mass is a base unit
Steve measures brightness is a base unit.
