## **Core Concept**
The question tests understanding of recombinant DNA technology and the characteristics of the genes used for transformation, specifically the GFP (Green Fluorescent Protein) gene and the Luciferase gene. GFP emits green light under UV excitation, while Luciferase catalyzes a reaction that produces light.

## **Why the Correct Answer is Right**
The Luciferase gene, when expressed, encodes for the enzyme luciferase, which catalyzes a reaction involving luciferin and oxygen, resulting in the production of light (bioluminescence). This reaction does not require external excitation light, allowing the plant to glow spontaneously in the dark. On the other hand, GFP (Green Fluorescent Protein) requires ultraviolet (UV) light excitation to emit green light; it does not produce light spontaneously in the dark.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because GFP requires UV light to fluoresce and will not glow spontaneously in the dark.
- **Option B:** This option is incorrect for the same reason as Option A; both plants' characteristics are described, but the question focuses on which glows spontaneously in the dark.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that Luciferase is often used in bioluminescence assays due to its ability to produce light without the need for external excitation, making it useful for detecting specific biological processes or for creating glowing plants or animals. This technology has various applications in research, agriculture, and even medical diagnostics.

## **Correct Answer:** . Luciferase gene.