What things had the speaker never learned?

The choice indicating military discipline is correct as it reflects the content being addressed by the speaker regarding their experiences and skills they have not acquired. The speaker may discuss unfamiliarity with structured lifestyles or hierarchical systems typically associated with military training. In contexts where the speaker reflects on personal growth, the mention of military discipline suggests that they have not engaged in training that emphasizes strict protocols, order, or the specific skills associated with military life.

The other options—social skills, cooking, and life skills—each pertain to more universal experiences or competencies that most individuals encounter in various contexts. Social skills refer to the ability to interact with others in everyday situations; cooking encompasses basic culinary practices that many learn through family or cultural traditions; and life skills include practical competencies needed for managing daily living, which are commonly taught in various educational and social settings. None of these are as specialized or contextual as military discipline, making that choice the most fitting response based on the speaker's narrative.