Final answer:
Karen Horney's concept of self-realization influenced Abraham Maslow, who is known for his hierarchy of needs and the concept of self-actualization, reflecting the pursuit of an individual's potential.
Step-by-step explanation:
Karen Horney's concepts of the real self and self-realization were influential in the development of humanistic psychology, which emphasizes the growth potential of healthy individuals. The theory that specifically used Horney's work on self-realization is most closely associated with Abraham Maslow. Maslow is famous for proposing the hierarchy of needs, which culminates in self-actualization—the realization of an individual's potential.
Therefore, the answer to the original question is Abraham Maslow (c). Maslow's theories contributed significantly to our understanding of the self, along with the work of other humanistic psychologists such as Carl Rogers. They both emphasized free will and self-determination, with individuals striving to become the best they can be, a process that reflects the pursuit of self-realization—a concept also essential to Horney's psychological framework.