B. A pot of boiling water represents a system that is completely open.
Answer: 
Explanation:
The density 
of a material is given by:
(1)
Where:
is the mass of the cube
is the volume of the cube
Now, the volume of a cube is equal to the length 
of its edge to the power of 3:
(2)
If we know 
, the volume of this cube is:
(3)
Substituting (3) in (1):
(4)
This is the density of the cube
Scientific knowledge is based upon observation, and it is supplemented by experimentation.<span> Scientific research follows the scientific method, a four-step process that guides scientists in the accumulation of knowledge.</span>
