The purpose of the advertisements is to sell the products to the customers. Using survey, advertisers develop insight about this. The advertisement does not always provide product details. Indeed, the concept of the product details is the result of the survey, but it does not mean that the concept has to be shown in the advertisement.
Options A and D are very close answers to the question. Catchy slogan does not add exact persuasiveness to the advertisement. Indeed, persuasive advertisement for the product shows the product for the needs of the customers. Therefore, the correct answer is D.
I'm not exactly sure, but to use common sense, I'd say eye-contact. You explicitly said, "nonverbal," and eye-contact is the most reasonable one.
@Molpoing D.Last summer Jim mowed just one lawn, but now he mows three that dose not correct the run on sentence.
