This is a test of commonsense. Complete the next sentence:

How to extract your dna
Create a mouth rinse.
To extract your dna from saliva, you'll need to create a mouth rinse first. You'll be mixing salt into water, because salt provides a rough, granular texture to help collect cells from your mouth.
It also helps protect the negative phosphate ends of your dna, allowing it to precipitate out of the saliva. Mix one tablespoon of salt into 500 milliliters of clean drinking water.