Explanation:

- Section 84 of the Indian Penal Code (IPC) addresses the defense of insanity and holds that an individual can be exempted from criminal responsibility if, at the time of committing the act, they were incapable of understanding the nature of the act due to unsoundness of mind.

- Medical Insanity: Refers to a clinical diagnosis of a mental disorder. It is assessed by healthcare professionals.

- Legal Insanity: Concerns the individual's capacity to understand the nature of their act and distinguish right from wrong in the context of the crime. It involves a legal standard applied during trials.

- Moral Insanity: It is not a recognized term under the IPC and generally refers to behavior that may lack a moral sense but not necessarily linked to a mental disorder.

- None: This option is incorrect as Section 84 specifically provides for a defense related to unsoundness of mind affecting one's legal responsibility.

Correct Answer: Option 2 - Legal Insanity