Final answer:
a. is fluorescent
The paint pigment described is fluorescent, as it absorbs red light and emits blue light through a process involving the excitation and emission of light at different wavelengths.
Step-by-step explanation:
A pigment molecule is capable of absorbing certain wavelengths of light and reflecting others, which accounts for its color. When materials such as fluorescent dyes are involved, these can absorb one color of light and emit another. In fluorescence, energy absorption causes electrons within the dye molecules to jump to higher energy states before falling back down to their ground states, emitting specific wavelengths of light. The emitted light is of lower energy and therefore of a lower frequency than the absorbed ones. For example, a material that absorbs ultraviolet light may emit visible light. Conversely, phosphorescent materials emit the absorbed light over a longer period of time, which is how glow-in-the-dark objects work.
The answer to the student's question is (a) fluorescent. A paint pigment that absorbs red light and gives off blue light would be considered fluorescent because it absorbs energy at one wavelength and emits it at a different wavelength. This pigment does not simply reflect or filtrate light; instead, it undergoes a process where the absorbed light is converted and re-emitted at a different wavelength. Pigments such as chlorophyll absorb light at specific wavelengths, leading to the reflection of the wavelengths that we perceive as the pigment's color.