A tint is specifically defined as a variation of a color that is achieved by adding white to the original hue. This process lightens the color, resulting in a softer and often pastel version of the original shade. When you add white to a color, it decreases the saturation and darkening effect, which is why tints are commonly used in design and art to achieve lighter and more delicate appearances.
The other options do not align with the definition of a tint. For example, claiming that a tint is darker than the original hue describes a shade, which is obtained by adding black. Describing a tint as the purest form of a color refers to the original hue itself, not the tinted version. Lastly, adding gray results in a tone rather than a tint, as tones are modified versions of colors that possess both a reduction in saturation and brightness.