Watching total solar eclipse is to wear professional glasses. Yongkang brand and moderate brand eclipse glasses use the same quality lenses. Because the price of Yongkang brand eclipse glasses is lower, when you buy Yongkang brand instead of moderate brand eclipse glasses, I bought glasses with the same viewing effect at a lower price. Which of the following, if true, is a prerequisite for the above conclusion? ['The price of eclipse glasses mainly depends on the price of the lenses.', 'These two are less expensive than other brands on the market.', 'The viewing effect of eclipse glasses is determined only by the quality of the lenses.', 'Yongkang eclipse glasses sell more than moderate eclipse glasses.']