Based on the splash size ranking provided in the table, object W has the highest rank of 2, while object Z has a rank of 3, object X a rank of 4, and object Y a rank of 1. Since splash size is influenced by factors such as mass, it is reasonable to assume that the object with the largest splash (highest rank) likely has the greatest mass. Therefore, the object that most likely has the greatest mass is:
object X.
It appears there was a misunderstanding in the provided responses, as the correct answer based on the ranking should indicate object X (rank 4, largest splash), but it seems missing in the options provided.