## Core Concept
The enquiry into the circumstances of death is a crucial process in determining the cause and manner of death. This process involves a thorough investigation into the events surrounding the death to gather relevant information. It is an essential aspect of forensic medicine and public health.

## Why the Correct Answer is Right
The correct term for the enquiry into the circumstances of death is **Inquest**. An inquest is a judicial inquiry in common law jurisdictions that determines the cause of a person's death. It is usually conducted by a coroner or a similar official and may involve a jury. The primary goal of an inquest is to establish the facts surrounding the death, which can help in identifying potential criminal activity or public health issues.

## Why Each Wrong Option is Incorrect
- **Option A:** While an autopsy is a medical examination of a deceased person to determine the cause of death, it is not the enquiry into the circumstances of death but rather a part of the investigation process.
- **Option B:** A post-mortem examination is essentially synonymous with an autopsy and does not refer to the enquiry into the circumstances of death.
- **Option C:** Inquests are specifically focused on the enquiry into the circumstances of death, making this option potentially correct, but let's evaluate all options.

## Clinical Pearl / High-Yield Fact
A key point to remember is that an **Inquest** is not just about determining the cause of death but also about understanding the circumstances leading to it, which can have legal and public health implications. This process helps in identifying potential areas for intervention to prevent future deaths.

## Correct Answer Line
**Correct Answer: D. Inquest.**