**Core Concept:** Signs of antemortem injury refer to observations or findings that indicate an injury occurred before death. These can be used to establish the cause of death and help in forensic investigations.

**Why the Correct Answer is Right:** Signs of antemortem injury are typically observed in post-mortem examinations and are not directly related to the primary cause of death. The correct answer is A, "signs of postmortem lividity," as they arise after death due to blood pooling in dependent areas.

**Why Each Wrong Option is Incorrect:**

1. **Option B ("Administering drugs after death"):** Administering drugs after death would not result in any observable signs and is unrelated to the primary cause of death.
2. **Option C ("Swelling of the hands and feet"):** Swelling of the hands and feet occurs after death due to loss of vascular tone and is not a sign of antemortem injury.
3. **Option D ("Increased rigor mortis"):** Increased rigor mortis occurs after death due to cessation of muscle enzymes and is not a sign of antemortem injury.

**Clinical Pearl / High-Yield Fact:**

**Correct Answer:** C ("Swelling of the hands and feet")

Forensic pathologists often look for signs of antemortem injury in a post-mortem examination to help determine the sequence of events before death and rule out potential external causes of death. Swelling of the hands and feet is a sign of antemortem injury because it indicates an increase in blood volume in these areas, which could have resulted from trauma or other events occurring before death (e.g., hypotension, cardiac arrest, etc.). This information can be crucial in establishing the cause of death and contributing to the overall understanding of the circumstances surrounding the deceased's demise.