Explanation of all the options:

1.in any case

• Explanation: This phrase is used to indicate that something is true regardless of the circumstances. It does not convey the same sense of conclusion as "in the end."
• Incorrect ❌

2.at least

• Explanation: This phrase typically suggests a minimum level or a consolation, which does not fit the context of the sentence. It does not imply a conclusion or finality.
• Incorrect ❌

3.by the end

• Explanation: While this phrase indicates a point in time, it doesn’t carry the same connotation of finally revealing something or concluding a thought as "in the end."
• Incorrect ❌

4.finally

• Explanation: This word conveys a sense of conclusion or resolution after a period of time or discussion. It aligns well with the context of the sentence, indicating that after denying the action repeatedly, he ultimately confessed.
• Correct ✅

5.None of the above

• Explanation: This option would imply that none of the provided choices are suitable. However, since "finally" is a fitting alternative, this option is incorrect.
• Incorrect ❌