Performance Records for 18 Salespersons Are Selected to Investigate Whether $\alpha$

Multiple Choice

Performance records for 18 salespersons are selected to investigate whether compensation methods are a significant motivational factor.
A Kruskal-Wallis test is to be performed with $\alpha$ = 0.01.The null hypothesis is _______.

A) Group 1 = Group 2 = Group 3
B) Group 1 $\neq$ Group 2 $\neq$ Group 3
C) Group 1 $\ge$ Group 2 $\ge$ Group 3
D) Group 1 $\le$ Group 2 $\le$ Group 3
E) Group 1 $\le$ Group 2 ≥ Group 3