Answer:
B:measure one side with a ruler and multiply that number by itself three times
Explanation:
A cube is closed box having equal sides. The length, width and height of a cube are equal.
We know that volume of a cube =

or volume of a cube = side x side x side
Therefore by multiplying one side of the cube three times by itself we will get the volume of the cube.
Thus, by measuring one side of the cube and then by multiplying that number three times by itself, we will be able to find the volume of the cube in the fastest way since all sides are equal in a cube.