Final answer:
Ayn Rand's philosophy doesn't provide a clear definition of 'ego' as per the options given, but option c) 'Rand defines ego as the driving force behind human progress.' could be seen as aligning with her broader views on rational self-interest.
Step-by-step explanation:
How does Ayn Rand define ego? Ayn Rand's philosophy often emphasizes the individual and their rational self-interest. However, the answer options provided do not directly correspond to a specific quote from Rand's works about the ego. Therefore, a comprehensive answer would require a deeper look into Rand's philosophy, Objectivism. Objectivism posits that the pursuit of one's own happiness, or self-interest, is the highest moral purpose of one's life. Thus, while c) - defining ego as the driving force behind human progress - resonates with her philosophy, it's not an explicit definition given by Rand herself.
Unlike Rand's Objectivism, existentialism emphasizes that the essence of an individual is not predetermined and that individuals are responsible for their own development through acts of the will. As such, Ayn Rand's conception of ego would be more about the conscious, rational self which pursues personal values and happiness rather than fitting within the psychoanalytic or existential frameworks described in the secondary information provided.
When considering ethical egoism, it broadly aligns with Rand's view that one's own self-interest is ethical and that each individual should act in a way that is rational and benefits themselves. Therefore, while the original multiple-choice question doesn't present a direct definition coming from Rand, option c) could be seen as loosely consistent with her overarching philosophy.