If your aplomb is shaken, what do you lack?

When your aplomb is shaken, it means that your self-assurance or composure has been upset. The term "aplomb" refers to a state of self-confidence and poise in difficult situations. Therefore, lacking aplomb indicates a loss of that confidence. The ability to maintain one's composure is directly tied to self-confidence, which is why the correct answer is self-confidence. Being able to navigate challenges with a sense of assurance is crucial in both personal and professional situations, and when that is compromised, it reflects an absence of self-confidence.

In contrast, ambition, determination, and patience, while important traits, do not directly relate to the concept of aplomb. These qualities encompass different aspects of motivation and emotional resilience, but they do not specifically address the notion of maintaining confidence under pressure.