**Core Concept**
Entomology, the study of insects, plays a crucial role in estimating the post-mortem interval (PMI) in forensic medicine. The presence and development of insects on a cadaver provide valuable information about the time since death.

**Why the Correct Answer is Right**
The correct answer is related to the fact that insects undergo a predictable life cycle, which can be used to estimate the PMI. Insects such as blowflies (Chrysopsidae) and flesh flies (Sarcophagidae) are attracted to the cadaver and start laying eggs. The eggs hatch into larvae, which feed on the soft tissues, and eventually pupate. The rate of development and growth of these insects is temperature-dependent, allowing forensic entomologists to estimate the time elapsed since death. This method is particularly useful in cases where other methods of estimating the PMI are inconclusive.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as entomology is not used to determine cause of death.
**Option B:** This option is incorrect as entomology is not used to determine the identity of the deceased.
**Option C:** This option is incorrect as entomology is not used to determine the manner of death.

**Clinical Pearl / High-Yield Fact**
The study of entomology in forensic medicine is often referred to as "forensic entomology" and has been used in various high-profile cases to estimate the PMI and solve crimes.

**Correct Answer: C. Estimating the post-mortem interval (PMI)**