The Main Idea of a Chi-Square Test Is to

The main idea of a chi-square test is to

A) test the estimated degree of fit (proportion of variance accounted for) of one variable to the other variable.
B) compare the estimated population means,to see if they vary from each other by more than chance.
C) compare estimated population variances,to see if they vary from each other by more than chance.
D) test how well the pattern of observed frequencies fits some expected pattern of frequencies.