To determine which box has the greatest density, we need to consider both the mass and volume of the contents in each box. Since all boxes have the same volume, we can deduce that the box with the greatest mass also has the greatest density.
From the information provided, the order of the boxes from least to greatest mass is:
- Paper clips (least mass)
- Dice
- Marbles
- Sand (greatest mass)
Since sand has the greatest mass among the four items, we conclude that the box filled with sand has the greatest density.
Thus, the answer is: A. the box filled with sand.