What effect is produced by adding a little black to primary blue?

Correct answer: A darker shade of blue will form

Adding a small amount of black lowers the lightness or value of blue, making it appear darker. In colour theory, a colour mixed with black is called a shade, so option D is correct. A tint is made by adding white, not black. The blue does not become a secondary colour because no second hue is mixed to create it, and adding black does not make blue warmer. The main concept is the difference between shade, tint, and hue.