**Core Concept**
Postmortem lividity, also known as livor mortis, is the discoloration of the skin due to the pooling of blood in the dependent parts of the body after death. This phenomenon is crucial in forensic medicine as it provides valuable information about the circumstances surrounding death.

**Why the Correct Answer is Right**
The time since death (B) and the position of the body at the time of death (D) are relevant factors in determining postmortem lividity. The lividity pattern can help estimate the time elapsed since death and the position of the body during the early stages of decomposition. However, the manner of death (C) is not directly related to postmortem lividity. The medicolegal importance of postmortem lividity lies in its ability to provide clues about the circumstances surrounding death, such as the cause of death elsewhere (A), which can be inferred from the lividity pattern.

**Why Each Wrong Option is Incorrect**
**Option A:** While postmortem lividity can provide information about the cause of death, it is not a direct indicator of the cause of death elsewhere. However, it can be used in conjunction with other evidence to infer the circumstances surrounding death.
**Option B:** Time since death is an important aspect of postmortem lividity, as the lividity pattern can change over time. The lividity pattern can help estimate the time elapsed since death, but it is not the only factor.
**Option C:** Manner of death refers to the circumstances surrounding death, such as homicide, suicide, or accident. Postmortem lividity does not provide direct information about the manner of death.
**Option D:** Position of the body at the time of death is an important factor in determining postmortem lividity. The lividity pattern can be influenced by the position of the body, which can provide clues about the circumstances surrounding death.

**Clinical Pearl / High-Yield Fact**
Postmortem lividity is a critical aspect of forensic medicine, and its pattern can provide valuable information about the circumstances surrounding death. It is essential to consider the time since death, position of the body, and other factors when interpreting postmortem lividity.

**✓ Correct Answer: C. Manner of death**