Answer:
Neuroticism.
Explanation:
The five-factor model is a personality determining factor used to help with a person's character. This Big Five factor provides the factors for what type of personality a person has, depending on certain factors or determiners.
According to this five-factor method, there are five underlying factors of personality, namely, agreeableness, openness to experience, extraversion, neuroticism, and conscientiousness. And according to this model, Ian's feeling of being "not good enough" or that he's being "treated unfairly" at work by his boss are characteristics of neuroticism. In this characterization, a person feels moody, sad, incapable, unstable emotionally, etc.