The laboratory has four beakers, and a small note is placed under each beaker: the first reads "Sulfuric acid in all beakers"; the second reads "This cup is sodium chloride"; the third One reads "This cup is not water", the fourth reads "Some beakers do not contain sulfuric acid". If only one sentence of the four beakers is true, which of the following must be true? ['Sulfuric acid in the first beaker.', 'Sodium chloride in the second beaker.', 'Water in the third beaker.', 'Not sulfuric acid in the fourth beaker.']