Final answer:
Rex exhibits the Big Five personality trait of Conscientiousness, which is characterized by high levels of performance and reliability.
Step-by-step explanation:
Rex exhibits the Big Five personality trait of Conscientiousness. This trait is associated with individuals who exhibit competence, self-discipline, thoughtfulness, and goal-directed behavior, leading to high levels of performance and reliability.
Conscientiousness is one of the five factors in the widely accepted Five Factor Model of personality, which also includes openness to experience, extraversion, agreeableness, and neuroticism.