**Core Concept**
Cadaveric rigidity, also known as rigor mortis, is a temporary stiffness in the muscles of a deceased body after death. It occurs due to the cessation of ATP production and the subsequent breakdown of actin and myosin filaments in the muscle cells, leading to an inability to relax the muscles.

**Why the Correct Answer is Right**
The correct answer is related to the mechanism of rigor mortis. In cases where cadaveric rigidity lasts longer than usual, it may indicate poisoning with substances that interfere with the normal breakdown of ATP or the relaxation of muscle cells. One such substance is anticholinesterases, which inhibit the enzyme acetylcholinesterase responsible for breaking down acetylcholine, a neurotransmitter that stimulates muscle contraction.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the mechanism of rigor mortis or prolonged cadaveric rigidity.
**Option B:** This option is not directly related to the breakdown of ATP or muscle relaxation.
**Option C:** This option is not a known cause of prolonged cadaveric rigidity.

**Clinical Pearl / High-Yield Fact**
Anticholinesterases, such as organophosphates, can cause prolonged rigor mortis due to their inhibition of acetylcholinesterase, leading to an accumulation of acetylcholine and sustained muscle contraction.

**Correct Answer:** C. Organophosphate poisoning.