Regina's grandmother is teaching her how to make mayonnaise. She explains that mayonnaise is made using oil, salt, vinegar (or lemon juice), and egg yolks. Lecithin in the egg yolks acts an emulsifier. What's an emulsifier?
a) An emulsifier makes foods separate into oily and watery portions
b) An emulsifier bleaches foods white
c) An emulsifier reduces acidity of a food
d) An emulsifier is a substance that helps fat-soluble and water-soluble compounds mix with each other