B) I'm assuming Stolas literally knows the recipe for every herb based tincture, potion, and elixir & will subsequently grant that knowledge to me because he is a good demon.
A is also a good choice because of that. I bet Stolas knows the secrets of astronomy (how do I travel as fast as light easily) & could point me towards life on another planet.
Under capitalism, herb knowledge could be parlayed into a career consulting for frou-frou restaurants. Travel the world, eat delicious food, critique the herbage, eat even more delicious food informed by your herb knowledge. Under communism, gimme that fancy strut #6.