At what systemic level do we start to see living beings making decisions rather than purely chemical reactions?

Starting from a molecule on up, to cells and beyond, at what system level is a being actually making a decision rather than reacting to their chemical environment based on purely chemical laws? For example, the molecules in a cells are solely reacting to their environment based on chemical fundamentals. However, a person thinks things through and makes decisions. Where in that range do we see decisions start to emerge?