Flexibility of Advance and Specialize Chemistry?

Is Two Component Chemistry the ability to use UP TO two components, or MUST you use two?

Can an Advanced Apothecary with 2 Component Chemistry opt to consume a use of 2CC to make a simple 1 component elixir? And can you use only 2 components with a use of 3 Component Chemistry as well?

I realize it’s a “waste” since those skills cost more CP per use to buy which is why it might fly, but it also makes those skills pretty flexible and I’m not sure if that “power” was intended.