The Null Hypothesis States That the Difference in Two Groups

The null hypothesis states that the difference in two groups population parameter is:

A) less than 1; there is no significant difference between the groups.
B) less than 0 (a negative number) ; showing a directional difference between the groups.
C) the same as the alternative hypothesis; no difference between the hypotheses.
D) equal to zero; there is no difference between the groups.
E) equal to zero; there is a difference between the groups.