## **Core Concept**
DNA testing in an autopsy setting often requires a tissue sample that is rich in DNA and can be easily obtained and preserved. The goal is to collect a sample that will yield high-quality DNA for analysis.

## **Why the Correct Answer is Right**
The correct answer, **D. Blood**, is not explicitly listed, but assuming it's related to a commonly used sample for DNA extraction: Blood is a rich source of DNA, specifically from white blood cells. However, in the context of autopsy and common practices, another tissue that stands out for its utility in DNA analysis is **liver (C)** or more commonly, **heart blood (D)** or **tissue like spleen or liver**. But if we consider standard practices and assuming **. ** relates to a specific commonly used tissue:
- **Liver (C)**: The liver is a good source of DNA because it is a nucleated organ and can provide a large amount of tissue for analysis.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because, although brain tissue can be used for DNA analysis, it's not the first choice due to potential degradation and the difficulty of the sampling process in an autopsy setting.
- **Option B:** This option is incorrect as it is not specified; however, if it relates to a less commonly used or inappropriate sample for DNA testing, it would be incorrect for that reason.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that for DNA analysis in an autopsy, **fresh or properly preserved tissue samples** are crucial. Among the commonly used samples, **heart blood** is often preferred because it's easily accessible and can provide a good source of DNA.

## **Correct Answer:** .