**Core Concept**
DNA staining is a crucial technique in histology and cytology, used to visualize and identify cells with specific characteristics. The ideal stain for DNA should selectively bind to DNA molecules without interfering with other cellular components.

**Why the Correct Answer is Right**
The correct answer is Acridine Orange (AO). AO is a fluorescent cationic dye that selectively intercalates into DNA, making it a specific stain for DNA. This occurs due to the electrostatic attraction between the positively charged AO molecule and the negatively charged phosphate groups in the DNA double helix. AO's ability to intercalate into DNA results in a distinct green fluorescence under UV light, making it an ideal stain for DNA.

**Why Each Wrong Option is Incorrect**
**Option A:** H&E stain is a general-purpose stain used for histological examination, but it is not specific for DNA staining. It stains both DNA and proteins, making it unsuitable for DNA-specific visualization.
**Option B:** Methylene blue is a basic dye that stains nucleic acids, but it is not as specific for DNA as Acridine Orange. It can also stain other cellular components, leading to non-specific results.
**Option C:** Giemsa stain is a supravital stain used for cytological examination, but it is not specific for DNA staining. It stains both DNA and proteins, and its staining pattern can vary depending on the cell type.

**Clinical Pearl / High-Yield Fact**
Acridine Orange is often used in flow cytometry to analyze cell populations and detect apoptosis. It can also be used to visualize DNA damage and repair mechanisms in cells.

**Correct Answer:** C.