Answer:
b
Block B has the greatest density.
Explanation:
density = mass/volume
volume = length × width × height
All blacks have the dimensions 7 cm by 3 cm by 1 cm, so the 3 volumes are equal.
Since density = mass/volume, and the volumes are equal, the block with the highest mass has the highest density.
Since all the masses are different, all densities are different.
Answer: Block B