Product Researchers Studied the Relationship Between Their Cola and a Composite

Product researchers studied the relationship between their cola and a composite happiness scale.The null hypothesis was retained.They should state that

A) drinking their cola does not cause depression.
B) their cola has no relationship to the happiness of its drinkers.
C) there is not enough evidence to suggest a relationship between drinking their cola and happiness.
D) their design was not powerful enough to find a significant relationship.