**Core Concept**
The estimation of the time since death, also known as post-mortem interval (PMI), is a crucial aspect of forensic pathology. It involves various methods to determine the elapsed time between death and the moment of examination. These methods rely on the decomposition process, the presence of livor mortis, rigor mortis, algor mortis, and other post-mortem changes.

**Why the Correct Answer is Right**
The correct answer involves identifying the method that is not applicable for estimating time since death. For instance, livor mortis, or post-mortem lividity, can be used to estimate the time since death, as it appears within 30 minutes to 2 hours after death and becomes fixed within 6-12 hours. Rigor mortis, on the other hand, sets in approximately 2-4 hours after death and resolves within 24-36 hours. Algor mortis, or cooling of the body, can also be used to estimate time since death, as a body cools at a rate of 1.5°F (0.8°C) per hour in a room temperature of 70°F (21°C). However, the decomposition process, which involves the breakdown of tissues by microorganisms, is highly variable and unreliable for estimating time since death.

**Why Each Wrong Option is Incorrect**
**Option A:**
* Not enough information is provided to determine if this option is correct or incorrect.

**Option B:**
Not applicable. This option may be a valid method for estimating time since death, such as the use of insects or other entomological evidence.

**Option C:**
Not applicable. This option may be a valid method for estimating time since death, such as the use of stomach contents or other post-mortem changes.

**Option D:**
Not applicable. This option may be a valid method for estimating time since death, such as the use of rectal temperature or other post-mortem changes.

**Clinical Pearl / High-Yield Fact**
One of the most reliable methods for estimating time since death is the use of rectal temperature, as it remains relatively constant for a short period after death.

**Correct Answer: B. B.**