Please choose the correct ending to complete the given sentence: Education and Communications: [header] How to make a water bottle cap pop off with air pressure [title] Obtain an empty plastic bottle. [step] This experiment works best with a bottle that has relatively thin plastic. You need to be able to twist the bottle, so bottles made of thicker plastic will be difficult to use.

Ending1: Carefully pick up the bottle with your fingers to ensure that it is clean, undented, and dry. Don't dump water onto the bottle while it is still in its cap, unless you want a quick, easy pop off effect. Ending2: You also want to use a standard size (16. 9 oz or 500 ml) bottle or larger, not the miniature ones. Ending3: [substeps] Glass bottles or even the kind sold with visors will be easier to use, as the plastic caps do not move the air around. [title] Get a sheet of aluminum foil and a small cup. Ending4: [substeps] If the bottle has any holes, small rocks, or other obstacles in the cut, twist the bottle several times to loosen the parts of the cap. You can also spread the bottle upside down on its side to wedge it.

Answer format: ending1/ending2/ending3/ending4