**Core Concept**
Cadaveric lividity, also known as postmortem lividity or livor mortis, is the discoloration of the skin due to the pooling of blood in the dependent parts of the body after death. The color of lividity can provide clues about the cause and timing of death. In this case, a bluish-green color is suggestive of a specific type of poisoning.

**Why the Correct Answer is Right**
The bluish-green color of cadaveric lividity is characteristic of carbon monoxide (CO) poisoning. Carbon monoxide binds to hemoglobin in the blood, forming carboxyhemoglobin, which imparts a bluish-green color to the skin. This is due to the shift of the oxygen-hemoglobin dissociation curve to the left, resulting in a decreased affinity of hemoglobin for oxygen. The presence of carboxyhemoglobin in the blood also leads to tissue hypoxia, which can cause cellular damage and death.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because cyanide poisoning typically causes a cherry-red color of the skin due to the inhibition of cytochrome c oxidase, which leads to an accumulation of oxygenated hemoglobin in the blood.
**Option B:** This option is incorrect because methanol poisoning typically causes a bright red or pink color of the skin due to the formation of formic acid, which leads to an accumulation of methemoglobin in the blood.
**Option C:** This option is incorrect because hydrogen sulfide poisoning typically causes a greenish-black color of the skin due to the formation of methemoglobin and sulfhemoglobin.

**Clinical Pearl / High-Yield Fact**
In cases of suspected carbon monoxide poisoning, the presence of carboxyhemoglobin in the blood can be confirmed using a carboxyhemoglobin (COHb) level assay. This test is particularly useful in diagnosing carbon monoxide poisoning in patients who are asymptomatic or have a delayed presentation.

**Correct Answer: D. Carbon monoxide poisoning.