The correct answer is individuals' degree of introversion or extroversion
Explanation: The MBTI is an instrument used to identify personal characteristics and preferences. It was developed the indicator during World War II, based on Carl Gustav Jung's Theories of Psychological Types. CPP Inc., publisher of the MBTI instrument, calls it "the most widely used personality assessment in the world", with up to two million assessments administered annually. The CPP and other advocates claim that the indicator meets or exceeds the reliability of other psychological instruments and includes reports of individual behavior.