Explanation:

- Option 1: Medical Insanity

- Refers to a mental condition diagnosed by medical professionals.

- Not always recognized in legal contexts for defense.

- Option 2: Legal Insanity

- Pertains to the inability to understand the nature of the act or distinguish between right and wrong at the time of the crime.

- This is what Section 84 of the IPC discusses.

- Option 3: Moral Insanity

- Concerns an individual who may act immorally but understands their actions.

- Not used for legal defense under Section 84.

- Option 4: Unsoundness of Mind of Any Kind

- Covers broader mental health issues without legal specificity.

- Section 84 specifically details criteria under legal insanity.