A 5-column table has 4 rows. The first column has entries A, B, C, Total. The second column is labeled X with entries 15, 5, 30, 50. The third column is labeled Y with entries 5, 8, 15, 28. The fourth column is labeled Z with entries 10, 7, 5, 22. The fifth column is labeled Total with entries 30, 20, 50, 100. Which two events are independent?