The correct answer is option 'D' - magnesium silicate.

Magnesium silicate, also known as talc, is a fluorescent material that can emit red color fluorescence under certain conditions. Let's delve into the details to understand why magnesium silicate exhibits this property.

Fluorescence:
Fluorescence is the phenomenon where a substance absorbs light at one wavelength and re-emits light at a longer wavelength. This re-emitted light is often of a different color than the absorbed light. Fluorescent materials contain certain molecules or atoms that can absorb energy from incoming light and then release that energy as light of a different color.

Explanation:
Magnesium silicate, or talc, is a naturally occurring mineral composed of magnesium, silicon, and oxygen. It is known for its softness and is commonly used in various industries, including cosmetics and ceramics. Talc can also exhibit fluorescence properties, depending on its composition and impurities present.

1. Composition:
Talc is primarily composed of magnesium silicate. The magnesium (Mg) ions and silicate (SiO4) tetrahedra form a crystal structure. This crystal lattice can incorporate impurities or defects, which can affect its fluorescence properties.

2. Activators and Defects:
Fluorescence in talc is typically attributed to the presence of activator ions or structural defects. These impurities or defects can create energy levels within the crystal lattice, allowing for absorption and emission of light at specific wavelengths.

3. Red Fluorescence:
In the case of magnesium silicate, specific activator ions or defects are responsible for the red color fluorescence. These activators or defects may involve energy transitions that result in the emission of light in the red region of the electromagnetic spectrum.

Conclusion:
Magnesium silicate, or talc, can exhibit red color fluorescence due to the presence of specific activator ions or structural defects within its crystal lattice. The absorption and emission of light at specific wavelengths result in the observed red fluorescence.