## Core Concept
The question pertains to the standard procedures for handling and examining animals postmortem in a laboratory setting, specifically in the context of experimental research. When conducting experiments involving animals like rats, it is crucial to follow proper protocols for euthanasia and postmortem examination to ensure the integrity of the research data and to comply with ethical standards.

## Why the Correct Answer is Right
The correct approach for a postmortem examination on dead rats during an experiment involves a thorough necropsy. A necropsy, or autopsy, is the examination of a dead body to determine the cause of death or to learn more about the disease process. In experimental settings, this procedure helps in understanding the effects of the experiment on the animal, verifying the efficacy of the experimental intervention, and ensuring that no unforeseen harmful effects occurred.

## Why Each Wrong Option is Incorrect
- **Option A:** This option is incorrect because it does not specify a recognized or standard procedure for postmortem examination.
- **Option B:** Similarly, this option lacks specificity and does not correspond to a widely accepted method for examining dead animals in experimental settings.
- **Option C:** This option might seem plausible but does not accurately represent the standard procedure for postmortem examination of experimental animals.

## Clinical Pearl / High-Yield Fact
A key point to remember is that any postmortem examination of animals used in research should be performed by trained personnel and should follow guidelines set forth by institutional animal care and use committees (IACUCs) or equivalent regulatory bodies. This ensures that the examination is conducted in a manner that is respectful, thorough, and compliant with ethical standards.

## Correct Answer: D. Necropsy.