Value in art refers to __ and __ brightness and dullness artificial and natural lightness and darkness worth and price

## Step 1<br />The problem is asking for the definition of 'value' in the context of art. The term 'value' in art refers to the lightness or darkness of a color. This is a fundamental concept in color theory, which is a branch of art.<br />## Step 2<br />The options provided are: brightness and dullness, artificial and natural, lightness and darkness, and worth and price. Among these options, 'lightness and darkness' is the correct definition of 'value' in art.<br />## Step 3<br />The other options, 'brightness and dullness', 'artificial and natural', and 'worth and price', do not accurately define 'value' in the context of art. 'Brightness and dullness' refer to the intensity of light, 'artificial and natural' refer to the origin of something, and 'worth and price' refer to the monetary value of something.