The answer is d. proportion. Proportion refers to the relative size of parts of a whole or the elements within an object. When we use proportion we are comparing certain parts of something to another or more parts of the rest of whatever you are doing. Take for example the human face. In order for a face to look realistic, you need to use proportion or it could end up looking kind of wonky. Proportion can also be used as a term in math when you are comparing numbers.
