The description of all decimals that are rational numbers is:
D. The decimal terminates or repeats.
Rational numbers are those that can be expressed as a fraction of two integers (where the denominator is not zero). Their decimal representations can either terminate (e.g., 0.75, which is equal to 3/4) or repeat (e.g., 0.333..., which is equal to 1/3). In contrast, irrational numbers have decimal representations that neither terminate nor repeat (e.g., the square root of 2 or pi).