Select from options: Continue writing the next sentence.

How to whiten teeth with baking soda 
Mix the baking soda with water or lemon (they both work fine). 
In a small cup, mix half a teaspoon of baking soda with a few drops of either water or lemon. Be sure it is a paste, this way it will be easier to apply.

OPT: [I] For applying the paste to your teeth you can use a toothbrush or just your fingers. If it is a bad stain you want to remove, it's recommended you apply the paste directly to the stain and let it set for about two minutes. [II] Rub the paste and leave it to sit for 10-15 minutes before spitting. Eat your mouth packed with baking soda. [III] You're ready to whiten your teeth! Do it fast and brush hard into the teeth! Don't forget to rinse! To whiten, get out a round tin cake pan. On each side of the pan, put two pans. [IV] Put it into your mouth and then grind it down. Little to no pressure can work for all of your teeth including those needing to be whitered.
Answer:
[I]