Final answer:
Dr. Sullivan is engaging in generativity through employment by continuing to teach and contribute to the growth of others, showcasing an active pursuit of personal growth and societal contribution in his later years.
Step-by-step explanation:
Dr. Sullivan is demonstrating generativity through employment. This concept encapsulates individuals who continue to find purpose in their careers by contributing to the growth and development of others, aligning with Erikson's stage of generativity versus stagnation.
The choice to keep teaching beyond traditional retirement age reflects a desire for continued personal growth and societal contribution, rather than stagnation. It illustrates a commitment to maintaining meaningful work and fostering the education and career preparation of young adults, indicative of a broader phenomenon where aging individuals, including the Baby Boomers generation, seek to maintain an active role in their society.