Final answer:
The correct option is B. A good waveguide desiccator is blue because desiccants like anhydrous cobalt(II) chloride are blue when dry and effective in indicating moisture absence. Color perception depends on which wavelengths of light are absorbed and which are reflected. Filters and object colors are determined by their absorption and reflection properties.
Step-by-step explanation:
The correct answer to the question of what color a good waveguide desiccator is would be blue. A waveguide desiccator is often used with materials that change color based on the presence of moisture. For example, anhydrous cobalt(II) chloride (CoCl2) is a blue color when dry but turns pink when it absorbs water. Therefore, materials that are a blue color are good indicators of the presence of dry conditions which is essential for a waveguide desiccator to be effective.
In reference to other information given, the light absorption properties can infer color perception. For instance, a blue filter typically absorbs all visible light except for blue light, which it reflects, making it appear blue to the observer. If a mixture of red and green light is shone on the subtractive colors, the color which is reflected depends on the subtractive color itself. Furthermore, when a white light is projected onto a blue tablecloth, the tablecloth reflects blue light and absorbs other wavelengths, which makes it appear blue to an observer.