William James, the Father of American Psychology, Once Wrote: "Thinking

William James, the father of American psychology, once wrote: "Thinking is for doing." What did he mean by this?

A) The human brain probably developed its current cognitive abilities in large part to enable effective decision-making and to facilitate behavior.
B) People typically engage in conscious thought only when engaged in a task (e.g., only when solving a puzzle, trying to construct an argument, or making a decision about something) .
C) Every behavior that a person engages in implies a particular thought or set of thoughts; researchers can therefore infer thoughts from behaviors.
D) Because the primary role of thoughts is simply to plan behaviors, the proper focus of study for psychologists is behaviors themselves (and not thoughts) .