**Core Concept**
Tardieu spots, also known as Tardieu's ecchymoses, are a post-mortem finding characterized by petechial hemorrhages or ecchymoses in the skin, particularly on the chest and abdomen. These spots are caused by the release of blood from small blood vessels due to putrefaction. Tardieu spots are an important sign in forensic pathology as they can indicate the cause of death.

**Why the Correct Answer is Right**
Tardieu spots are typically seen in cases of death due to drowning. When a person drowns, the lungs expand and become over-inflated, which causes the tiny blood vessels in the lungs to rupture. This leads to the release of blood into the alveoli, which eventually causes the blood to leak into the surrounding tissues, resulting in the formation of Tardieu spots. The release of blood from the lungs into the body's tissues is facilitated by the breakdown of the body's tissues due to putrefaction, which is a characteristic of drowning deaths.

**Why Each Wrong Option is Incorrect**
**Option A:** Tardieu spots are not typically seen in cases of hanging. Hanging causes congestion of the blood vessels in the neck, leading to petechial hemorrhages in the eyes and face, but not in the skin of the chest and abdomen.
**Option B:** Tardieu spots are not characteristic of death due to poisoning. Poisoning can cause a variety of post-mortem findings, but Tardieu spots are not a typical feature.
**Option C:** Tardieu spots are not seen in cases of trauma. Trauma can cause a variety of post-mortem findings, including hemorrhages in the skin, but Tardieu spots are specific to drowning deaths.

**Clinical Pearl / High-Yield Fact**
Tardieu spots are a classic post-mortem finding in drowning deaths, and their presence can be used as evidence of drowning in forensic pathology. However, it is essential to note that Tardieu spots can also be seen in other conditions, such as severe hypotension or cardiac arrest, so they should be interpreted in conjunction with other evidence.

**Correct Answer:** C.