Final answer:
Lincoln, with his cooperative behavior and satisfaction with his current role, is best described as an agreeable employee.
Step-by-step explanation:
Based on the description provided, Lincoln is most likely an agreeable employee. Agreeableness is one of the five personality traits in the Big Five personality trait model and refers to individuals who are cooperative, warm, and kind. Given that Lincoln enjoys his role, excels at calming customers, and is courteous and giving to colleagues, he displays traits that are characteristic of someone with a high level of agreeableness. He does not seem particularly driven by ambition or high levels of stress, which rules out being primarily conscientious or neurotic. His contentment with his professional situation also suggests he is not predominantly seeking new experiences, and the description does not provide enough evidence to suggest he is an extrovert. Therefore, of the provided options, the agreeable employee is the most fitting description for Lincoln.