Final answer:
The primary color that makes other colors appear lighter and brighter is yellow.
Step-by-step explanation:
The primary color that, when added to other colors, will make the color appear lighter and brighter is yellow.
In the subtractive color system used in painting, yellow is a primary color. When it is added to other colors, it can create lighter and brighter shades of those colors. For example, adding yellow to blue creates a lighter and brighter shade of green.
Similarly, in the additive color system used in computer screens and theater lighting, yellow is created by adding red and green light together. Mixing yellow light with other colors can also make them appear lighter and brighter.