Non-repudiation is a very desirable trait because it ensures that an action or transaction cannot be denied or disputed by the parties involved. Let's go through each option to understand why it is correct or incorrect:

Option A) It establishes traceability of every action to the doer - This option is correct because non-repudiation ensures that every action can be traced back to the person who performed it. This helps in establishing accountability and responsibility.

Option B) In some critical situations, it should be impossible to deny an action - This option is correct because non-repudiation prevents the ability to deny or dispute an action, especially in critical situations. This is important to ensure trust and reliability in such scenarios.

Option C) It is a forensic analysis mechanism - This option is incorrect. While non-repudiation can be used as a tool in forensic analysis, it is not the primary purpose of non-repudiation. Non-repudiation primarily focuses on preventing denial of actions or transactions.

Option D) All of the above - This option is correct because all the statements mentioned in options A and B are true. Non-repudiation establishes traceability, prevents denial in critical situations, and can be used in forensic analysis.

Therefore, the correct answer is D) All of the above. Non-repudiation is desirable because it establishes traceability, prevents denial in critical situations, and can be used as a forensic analysis mechanism.