Which of the Following Would NOT Be Allowed in an Ordinary

Which of the following would NOT be allowed in an ordinary application of the chi-square tests?

A) Participants' preference for studying sitting or lying down are assessed as sophomores and then again as seniors.
B) Tall and short people are compared on their religious affiliation.
C) The number of people of different ethnicities working in a particular company is compared to the proportions of those ethnicities in the general public.
D) The number of successes of an advertisement is compared for three different groups of consumers to see if the number of successes is equal for the three groups.