To determine which box has the greatest density, we can use the relationship between mass, volume, and density. The formula for density is:
\[ \text{Density} = \frac{\text{Mass}}{\text{Volume}} \]
Since all four boxes have the same volume, the density will depend solely on the mass of the contents of each box. According to the order provided from least to greatest mass:
- Paper clips
- Dice
- Marbles
- Sand
This means that the box filled with paper clips has the least mass and therefore the lowest density, followed by the box with dice, then the box with marbles, and finally, the box filled with sand has the greatest mass.
Since the mass is highest for the box containing sand and the volume is the same for all boxes, the box containing sand will have the greatest density.
Thus, the answer is:
A. the box filled with sand.