Susan,a Researcher,conducts a Study in a Vegetable Store

Multiple Choice

Susan,a researcher,conducts a study in a vegetable store.She observes the store's customers for a period of 3 days without their knowledge and notices that people are more likely to buy a bag of vegetables which they have sampled at random than those that have been sampled nonrandomly by the shopkeeper.Which statement is TRUE of Susan's observation?

A) The study is invalid,as the buyers were not informed of the expected outcome of the study.
B) Susan has failed to avoid demand characteristics in her study.
C) The buyers have considered random samples to be representative of the whole.
D) Susan has used the double-blind observation in her study.