**Core Concept**
Rigor mortis is a temporary stiffness of the muscles that occurs after death, caused by a series of complex biochemical and physiological changes. This process involves the transformation of ATP to ADP, leading to a shift in the concentration of ions within the muscle cells, ultimately resulting in muscle contraction and rigidity.

**Why the Correct Answer is Right**
The correct answer is related to the depletion of ATP stores in the muscle cells. After death, the normal cellular processes that maintain muscle tone cease to function, leading to a decrease in ATP levels. As a result, the actomyosin complex in the muscle cells undergoes a conformational change, resulting in muscle contraction and rigidity. This process is facilitated by the increased concentration of calcium ions within the muscle cells, which also plays a crucial role in the initiation of rigor mortis.

**Why Each Wrong Option is Incorrect**
**Option A:** This option does not accurately explain the underlying mechanism of rigor mortis. While muscle injury can lead to inflammation and cellular damage, it is not directly responsible for the development of rigor mortis.

**Option B:** This option is incorrect because the autolytic process, or self-digestion of tissues, is a separate phenomenon that occurs after death, but it is not directly related to the development of rigor mortis.

**Option C:** This option is incorrect because the release of histamine during anaphylaxis is a specific immune response that is not directly related to the biochemical changes that occur after death.

**Clinical Pearl / High-Yield Fact**
It is essential to note that rigor mortis typically begins to set in within 2-4 hours after death and peaks around 12-24 hours post-mortem. This process can be influenced by various factors, including the temperature, humidity, and the presence of certain enzymes.

**Correct Answer: D. Depletion of ATP stores**