Final answer:
A person who is described as careless and disorganized would likely have a low score in the Big Five trait dimension of conscientiousness, which is associated with organization and efficiency.
Step-by-step explanation:
A person who is careless and disorganized most clearly ranks low on the Big Five trait dimension of conscientiousness. The Big Five, which can be remembered with the mnemonic OCEAN, include openness, conscientiousness, extraversion, agreeableness, and neuroticism.
Conscientiousness is characterized by a high degree of organization, efficiency, self-discipline, thoughtfulness, and achievement-striving behavior. Individuals with low conscientiousness tend to lack organization and often appear disorganized and careless in their approach to tasks and responsibilities.