An Industrial-Organizational Psychologist Has Been Asked to Identify the Ways

An industrial-organizational psychologist has been asked to identify the ways in which high-stress and low-stress game designers are different. The psychologist comes up with the tentative explanation that the degree of control over one's work determines the designer's stress level. This tentative but objectively verifiable statement would constitute which step in the scientific method?

A) theory building
B) operationally defining the problem
C) proposing a hypothesis
D) gathering evidence through observations