Which fluorochrome is most commonly used for highlighting nucleic acids?

Acridine orange is a fluorochrome that is specifically utilized for highlighting nucleic acids due to its ability to bind selectively to DNA and RNA. When excited by a specific wavelength of light, acridine orange emits fluorescence, allowing visualization of nucleic acid structures in tissue samples. Its dual staining capability allows it to differentiate between double-stranded DNA, which fluoresces green, and single-stranded RNA or denatured DNA, which fluoresces orange/red.

Carmine, while a vivid stain used for various biological structures, does not have the specificity for nucleic acids that acridine orange possesses. Victorian blue is primarily used for staining collagen and does not target nucleic acids. Langhan's iodine is used in histological staining methods, particularly for highlighting glycogen, rather than for nucleic acids. Thus, acridine orange stands out as the most appropriate choice for highlighting nucleic acids, making it the correct answer.