The lamp might not be broken. Maybe the light bulb just burned out.

Explanation:
The given statement suggests that there is a possibility that the lamp is not broken. Instead, it could be a case of a burned-out light bulb. Let's break down the options and understand why option 'C' is the correct answer.

a) Must not:
- This option implies that it is certain that the lamp is not broken.
- However, the statement presents an alternative possibility, indicating that there is no certainty about the lamp being broken or not. Therefore, we can eliminate this option.

b) Could not:
- This option suggests that it is impossible for the lamp to be broken.
- However, the statement does not provide any information to support this claim. It only presents the possibility of a burned-out light bulb, which doesn't rule out the lamp being broken. Hence, we can eliminate this option as well.

c) Might not:
- This option indicates that there is a chance that the lamp is not broken.
- The statement supports this possibility by suggesting that the light bulb might have burned out, which could be the reason for the lamp not working. Therefore, this option aligns with the given information and is the correct answer.

d) None of these:
- This option suggests that none of the given options are correct.
- However, after analyzing the statement, we can see that option 'C' (Might not) is indeed the correct answer.

In conclusion, the correct answer to the given question is option 'C' (Might not) because the statement provides an alternative possibility of the light bulb burning out, indicating that the lamp may not be broken.