## Core Concept
The study of insects and their relationship to a deceased body is known as **Forensic Entomology**. It plays a significant role in estimating the post-mortem interval (PMI), which is the time elapsed since death. Forensic entomology helps in understanding the ecological and biological processes that occur during the decomposition of a body.

## Why the Correct Answer is Right
The correct answer, , is related to the estimation of the **post-mortem interval (PMI)**. Forensic entomology helps in determining the PMI by analyzing the presence, stage of development, and species of insects found on or near the cadaver. Different insects colonize the body at different times after death, and by studying their life cycles and succession patterns, investigators can estimate how long the body has been deceased.

## Why Each Wrong Option is Incorrect
* **Option A:** - This option is incorrect because while forensic entomology might indirectly help in understanding the circumstances of death, it is not directly used to find the **cause of death**.
* **Option B:** - This option is incorrect as forensic entomology is not primarily used to determine the **manner of death** but rather to estimate the PMI.
* **Option C:** - This option might seem related but is incorrect in the context provided because forensic entomology's primary application in this scenario is not listed here.

## Clinical Pearl / High-Yield Fact
A crucial point to remember is that **flies** and **beetles** are commonly used in forensic entomology. Flies, particularly blowflies, are often among the first to colonize a dead body, and their life cycle can provide a relatively accurate estimate of the PMI. The presence of certain species of flies and beetles and their developmental stages can help forensic scientists calculate the minimum PMI.

## Correct Answer: D. post-mortem interval.