Please choose the correct ending to complete the given sentence: Education and Communications: [header] How to simulate stomach acid [title] Use a cup of plain, white vinegar. [step] While vinegar is not as acidic as stomach acid, it can be used to simulate what a stomach does in a simple experiment. To use it, simply fill a cup with vinegar, and drop what you want to test into the cup.

Ending1: [title] Evaluate the beverage you're consuming for the amount of potassium in the liquid. [step] Green leafy vegetables are renowned for their potassium boosting properties. Ending2: Don't fill the cup or cup with water, or else you could damage the cups or lacks. [substeps] Try using mouthwash or tea filters instead. Ending3: [substeps] Vinegar must contain enough acid so that it commits to the bottom of the cup. Other methods can be using an ordinary measuring cup. Ending4: Vinegar ranks at about 2 on the ph scale, so it is about as acidic as stomach acid. [substeps] The acidity of stomach acid is usually in the range of 1 to 3 on the ph scale.

Answer format: ending1/ending2/ending3/ending4