Cooking Tip: Cornstarch Substitution

I was baking today but I didn't have any cornstarch so I went a search for a substitute and here's what I found:

For 1 tablespoon cornstarch:

Option 1:
substitute 2 tablespoons all-purpose flour;

Option 2:
1 tablespoon potato flour or rice flour;

Option 3:
4 teaspoons quick-cooking tapioca;

Option 4:
2 teaspoons arrowroot

Source