Please choose the correct ending to complete the given sentence: Education and Communications: [header] How to dissolve an eggshell [title] Gather your materials. [step] For this experiment you will need a fresh, uncooked egg, a drinking glass, a dissolving solution such as white vinegar or a cola beverage, and 4-5 days of patience. The drinking glass needs to be large enough for the egg to touch the bottom without touching the sides of the glass.

Ending1: You can optionally use a plastic bowl instead. [title] Cut the eggshell in half lengthwise. Ending2: Do not use a mixing bowl, or you risk breaking a glass. [substeps] You will need about 5 egg yolks and one cup of white vinegar. Ending3: [substeps] You can also use a plastic cup or container to hold the egg, but clear containers allow you to observe the experiment over time. Use a fresh egg because an older egg will float in the liquid. Ending4: To dissolve the eggshell you will need a tool that allows you to trace patterns on the shell. [substeps] A small flat pan or strainer will work well for melting eggshells.

Answer format: ending1/ending2/ending3/ending4