If the author's assessment of the use of heat pumps is correct, which of the following best expresses the lesson that advertisers should learn from this case? A. Do not make exaggerated claims about the products you are trying to promote. B. Focus your advertising campaign on vague analogies and veiled implications instead of on facts. C. Do not use facts in your advertising that will strain the prospective client's ability to believe. D. Do not assume in your advertising that the prospective clients know even the most elementary scientific principles. E. Concentrate your advertising firmly on financially relevant issues such as price discounts and efficiency of operation.