**Core Concept**
After death, cellular membranes lose integrity, leading to the release of intracellular potassium into the extracellular fluid, including the vitreous humor. This is a well-documented postmortem change due to the breakdown of cellular ion balance.

**Why the Correct Answer is Right**
At the time of death, cells undergo autolysis and membrane depolarization, resulting in the efflux of intracellular potassium into the surrounding fluids. The vitreous humor, being a fluid-filled space in the eye, also experiences this shift. Potassium is primarily intracellular, and its release into the vitreous postmortem leads to a measurable rise in potassium levels. This change is consistent across most causes of death and is used in forensic autopsies to assess postmortem interval.

**Why Each Wrong Option is Incorrect**
Option A: Potassium does not fall; instead, it increases due to cellular breakdown.
Option C: Potassium does not remain unchanged—active ion shifts occur postmortem.
Option D: The change in potassium is consistent regardless of cause of death, making this option incorrect.

**Clinical Pearl / High-Yield Fact**
In forensic medicine, a rise in vitreous potassium levels after death is a key indicator of postmortem changes and is used to assess the time of death. This change occurs within minutes to hours postmortem and is not influenced by the cause of death.

✓ Correct Answer: B. Potassium level increases