What combination of colors is used to create gray?

The combination of colors used to create gray is achieved by mixing white and black. This is because gray is a neutral color that lies between black and white on the grayscale. When equal amounts of black and white are mixed, the result is a true gray. By adjusting the balance of black or white, you can create various shades of gray, from lighter to darker.

Other combinations mentioned in the options do not directly create gray. For instance, primary colors or secondary colors do not inherently mix to produce gray; rather, they can produce a range of other hues when combined. Overall, the use of white and black to create gray highlights the fundamental understanding of color mixing in terms of value.