Tea is a healthy drink loved by Chinese people. Generally, after brewing and drinking tea several times, the leftover tea is discarded. An expert pointed out that in fact, the substances that can be dissolved in water are limited and a lot of nutrients The substance is still retained in the tea leaves, and it is a pity that they should be discarded in vain. People should eat the leftover tea. Which of the following, if true, can best refute the expert's point of view? ['Many non-nutritional substances in tea are not soluble in water.', 'Tea contains theophylline and trace elements, which can be refreshing.', 'Drinking tea for the average person has become a habit, not to absorb nutrients.', 'Many people leave the leftover tea to make tea cakes, tea eggs, etc.']