The correct option is C millilitre
SI unit of mass is kilogram (kg).
Other commonly used units of mass are gram (g), milligram (mg), pound, ounce, etc.
The SI unit of volume is metre cube (m3).
Other commonly used units of volume are litre (L), millilitre (mL), etc.
Hence, millilitre (ml) is an unit of measurement of volume, and not that of mass.