Sheldon and amy met on an online dating site. sheldon describes himself as stubborn, competitive, and argumentative. according to the big five trait theory, sheldon is most likely

Low in agreeableness

Explanation:

The Five-Factor Model of personality is a model of the structure of personality according to which human personality can be described using five broad dimensions: Extraversion, Agreeableness, Conscientiousness, Neuroticism, and Openness.

The main characteristics of the dimensions are:

Extraversion: Outgoing, socially confident behavior. Extroverts are sociable, talkative and enjoy being the center of attention. Introverts are more quiet and prefer to be on their own.Agreeableness: Individuals who score highly on agreeableness are friendly and co-operative, they are trusting of others and are more altruistic and sympathetic. People who score low on this dimension are less concerned with pleasing other people or making friends, they tend to be more suspicious and are less charitable, they are also competitive and stubborn.Conscientiousness: People who are conscientious are more aware of their actions and the consequences of their behavior than people who are unconscientious. They feel a sense of responsibility towards other people and are careful with their duties.  People who score low on this dimension are less careful and are less concerned about tidiness and punctuality.Neuroticism: People with high neuroticism are persistent worriers. They are fearful and often feel anxious, over-thinking their problems focusing on the negative aspects of them. They tend to become frustrated and angry if things don't go as they wish.  People who score low are less preoccupied and are able to remain more calm under stressful situations.Openness: Willingness to try new activities. People with higher levels of openness enjoy artistic and cultural experiences and are more open to unfamiliar cultures and customs, they are imaginative.  People with low levels of openness are wary of uncertainty and the unknown and feel uncomfortable in unfamiliar situations and prefer familiar environments.

In this example, Sheldon describes himself as stubborn, competitive and argumentative. We can see that the dimension that has to do with these characteristics is the agreeableness dimension. In particular, people who score low on this dimension are less concerned with pleasing other people (argumentative) or making friends, they tend to be more suspicious and are  competitive and stubborn. Thus, we can conclude that according to this theory, Sheldon is most likely low in agreeableness