Final answer:
The woman says 'I'm afraid you've seen too much' likely because the man knows a secret, which is dangerous for both of them, making option B the correct answer.
Step-by-step explanation:
In the context provided, it appears that the woman says, "I'm afraid you've seen too much," because she feels the man has come to know a dangerous secret due to the clues and behaviors he has observed. The man likely observed actions or overheard conversations that led him to unravel a secret that could pose a threat to the woman or to himself. This statement evokes a sense of peril associated with the knowledge he has acquired, indicating that the man is now in a position where his awareness of the secret makes him a potential liability.
Given this context, the most accurate interpretation of why the woman said, "I'm afraid you've seen too much," is option B: Knows a secret.