## **Core Concept**
The confirmatory test for blood stain identification is crucial in forensic science to determine the presence of blood. Blood contains **heme** and **globin** components, which can be targeted for identification. Various chemical and immunological tests can detect blood, but a confirmatory test specifically identifies human blood.

## **Why the Correct Answer is Right**
The **Techtigen absorption elution test (also known as the absorption-elution test)** and **precipitation test** are specific, but when it comes to confirming the presence of human blood, the **precipitation test (Ouchterlony test or double diffusion test)** is highly specific. This test involves the diffusion of antibodies and antigens towards each other in a gel medium, forming a precipitate if there's an antigen-antibody reaction. For blood typing and species identification, this test can confirm if a stain is indeed human blood by reacting with anti-human serum.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is blank and thus cannot be evaluated.
- **Option B:** This option is also blank and cannot be considered.
- **Option C:** Similarly, this option does not provide any information.
- **Option D:** This option is blank as well.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that while **benzidine** and **Kastle-Meyer** tests are sensitive for the presence of heme (indicative of blood), they are not specific for human blood. The **Ouchterlony test** or similar specific immunological tests are required for confirmation of human origin.

## **Correct Answer:** D. Precipitation test.