The independent variables in Part I, the ones intentionally manipulated, are the
A. Mass and type of material
B. Temperature and volume
C. Density and gravity

The independent variable in Part II, the one that is intentionally manipulated, is the
A. Mass
B. Type of material
C. Temperature

The dependent variable for both Parts I and II, the one that you measure the response in, is the
A. Mass
B. Type of material
C. Temperature