Answer:
Conscientiousness.
Explanation:
As per the question, a person who displays a careless as well as undisciplined or disorganized behavior would be most clearly ranked low on five big personality trait of 'conscientiousness' as he shows a lack of thoughtfulness(as he shows carelessness) and goal-oriented behavior(being disorganized). A person with high conscientiousness level would show more discipline and organization along with a variety of thoughts leading to accomplished goals which influences others. Therefore, the person(careless and disorganized) would be treated low on conscientiousness.