She is a lot more clever than we know.

Explanation:
- The phrase "a lot" is an idiomatic expression that means "much" or "significantly."
- It is used to emphasize the degree or extent of something.
- In this case, it is used to emphasize the level of cleverness possessed by the person in question.
- The sentence suggests that the person's cleverness exceeds our current understanding or perception of it.

Usage of "a lot":
- The phrase "a lot" is commonly used in informal speech and writing to express a large or considerable amount.
- It is often used to modify adjectives or adverbs, indicating a high degree or extent.
- For example, "He is a lot taller than me" or "She talks a lot faster than I do."
- In this sentence, "a lot" is used to modify the adjective "clever" and indicate a significant level of cleverness.

Comparison with other options:
- Option A ("some") suggests that the person is clever to some extent but does not convey the idea of a significant or noticeable difference in cleverness.
- Option B ("many") implies that the person is clever in multiple ways or possesses multiple clever qualities, but it does not convey the idea of an exceptional degree of cleverness.
- Option D ("none") suggests that the person is not clever at all, which contradicts the statement in the sentence.

Conclusion:
- The correct answer is option C ("a lot") because it accurately conveys the idea that the person is significantly more clever than we currently know or perceive.