If you were planning to buy a television set, the following advertisement would certainly attract your attention: "Color TV, only $79. Two day sale. Hurry." However, when you go to the store ready to buy, you may discover that the advertised sets are sold out. But the salesman is quick to reassure you that he has another model, a more reliable set which is "just right for you". It costs $359. This sales tactic is called "bait and switch". Buyers are baited with a sales offer, and then they are switched to another more costly item. Buying items on sale requires careful consideration of the merchandise and the reasons for the sale.

Q. Underline the sentence which clearly illustrates the main idea.