Answer:
Neuroticism
Step-by-step explanation:
The Big Five theory of personality consists of five distinct categories of personality including, conscientiousness, agreeableness, openness to experience, neuroticism, and extroversion.
Neuroticism: The term neuroticism is one of the major personality dimension in the Big-Five personality theory. It explains that an individual who is high on neuroticism personality is highly moody, and experiences feelings like fear, worry, frustration, envy, anxiety, anger, loneliness, and depression.
In the question above, Ian would likely score highly on the Big Five factor of neuroticism.