Answer:
First of all, the desire of the public is almost always going to have a pattern, as well as their fears, even though fearing something could be very individual, you still can find a pattern.
In this case, when you're advertising corn flakes, what you need to focus, besides the image, is the message that is being said, and in this case, you need to focus, not only on the quality of the product, but the desire to eat and what this will give you if you eat it, for example, iron. And by saying what you'll get with that, you focus on what happens if you don't get the iron inside the corn flakes, do I get sick? That's what the general public will think and then buy the product.