Final answer:
Hans Eysenck's initial personality model had two factors: extroversion/introversion and neuroticism/stability, focusing on the biological underpinnings of personality traits. The answer is option C.
Step-by-step explanation:
Hans Eysenck developed a model of personality that initially had two factors. These factors, as described by Eysenck and his colleagues, were extroversion/introversion and neuroticism/stability. This two-factor model, also known as Eysenck's Personality Inventory (EPI), suggests that these dimensions are sufficient to describe human personality.
Eysenck's theory emphasizes the biological basis of these traits, suggesting that our genetic inheritance plays a significant role in shaping our personalities. In contrast, the Five Factor Model, also known as the Big Five, includes five broad trait dimensions: openness to experience, conscientiousness, extroversion, agreeableness, and neuroticism, remembered by the mnemonic OCEAN.
While Eysenck's model was pioneering, it has been criticized for being too narrow compared to later models, such as the Big Five, which provide a more comprehensive view of personality traits.