Which of the following is NOT a color of the self variety in cavies?

The self variety in cavies refers to a classification in which the guinea pig is of a solid color throughout its body, without any other markings or patterns. The recognized colors in the self variety include pure and unbroken shades.

Black, blue, and red are all recognized colors within the self variety as they represent solid color options that can be beautifully displayed by cavies.

On the other hand, brindle is characterized by a combination of two colors, often presenting a striped or flecked pattern rather than a solid hue. This distinct pattern disqualifies brindle from being classified within the self variety, making it the correct choice for the answer. The nature of brindle is fundamentally different from self-colored variations, hence it does not belong to the same category.