the answer is c: kilogram
explanation: The standard International System of Units (SI) unit of mass is the kilogram (kg). The kilogram is 1000 grams (g), first defined in 1795 as one cubic decimeter of water at the melting point of ice.
I believe the answer is a
This would be B
Hope this helped
Out of the choices given, the statement about how light travels is "<span>Light can travel in a vacuum, and it travels faster if the light source is moving."</span>
