We just have to remember that density of an object is given by the quantity of matter that is located in a certain volume, so the more matter in the less volume the greater the density, so as we can see the B image is the one that has the most volume so that wouldn´t be the one with the highest density, the A has the same volume as the C but has less particles, so the one with the highest density would be C because has the less volume and the most particles.
