**Question:** Algor mortis is -

A. A decrease in skin temperature after death
B. An increase in skin temperature after death
C. A decrease in body temperature after death
D. An increase in heart rate after death

**Core Concept:**
Algor mortis, also known as pallor mortis, refers to a decrease in skin temperature that occurs after death due to the cessation of blood circulation and cellular activity. The core body temperature, however, remains relatively stable, as it is regulated by the hypothalamus and is not influenced by external factors.

**Why the Correct Answer is Right:**
Choice C (A decrease in body temperature after death) accurately describes algor mortis. Death results in the cessation of blood circulation and cellular activity, leading to a decrease in skin temperature. This process is a crucial step in the post-mortem examination as it helps forensic experts estimate the time since death occurred (post-mortem interval).

**Why Each Wrong Option is Incorrect:**
Option A (A decrease in skin temperature after death) is incorrect because it contradicts the actual physiological response observed after death.
Option B (An increase in skin temperature after death) is incorrect due to the opposite effect it describes compared to algor mortis.
Option D (An increase in heart rate after death) is incorrect, as heart rate remains unchanged or slightly increases due to rigor mortis, not algor mortis.

**Clinical Pearl:**
In forensic investigations, algor mortis can provide valuable information about the time since death occurred. By measuring the rate of temperature change, forensic experts can estimate the post-mortem interval, which is crucial for determining the time of death and supporting the investigation process.