In the table provided, the splashes are ranked from 1 to 4, with 4 being the largest splash and 1 being the smallest. The splash size rankings are as follows:
- Object W: 2
- Object X: 4
- Object Y: 1
- Object Z: 3
Since object X has the highest splash size ranking (4), it is most likely to have the greatest mass, as a larger splash typically results from a heavier object displacing more water upon impact.
Therefore, the object that most likely has the greatest mass is object X.