Which Study Could Be Rejected on the Grounds of Testimonial

Which study could be rejected on the grounds of testimonial data?

A) A study about the effects of herbicide on Japanese beetles was conducted in the laboratory using a sample size of 20 beetles.
B) A study about the effects of herbicide on Japanese beetles was conducted in Illinois using a 20 acre field as a study site.
C) A study about the effectiveness of antacids in a study group of of 200 people who suffer from ulcers.
D) A study about the impact zebra mussels have upon the Great Lakes.
E) A study consisting of 200 test subjects who are interested in a new weight loss pill.