Explanation:

- Discipline is often thought to limit freedom, which can lead to confusion about its true purpose.

- In this context, the sentence suggests that people commonly misunderstand what discipline means.

- Option 1: happily - This doesn't fit well because the context is about misunderstanding, not an emotion like happiness.

- Option 2: usually - This is the best fit because it conveys that the misunderstanding about discipline is common or frequent.

- Option 3: proudly - Pride doesn’t make sense here as it doesn’t connect with misunderstanding.

- Option 4: slowly - This implies a progression over time, unrelated to misunderstanding.