What visual aspect does a garnish contribute to a dish?

A garnish primarily contributes to the visual appeal of a dish, making it more attractive and inviting to the diner. Attractive plating is a fundamental aspect of culinary arts because presentation can significantly influence a diner's experience and perception of flavor. A well-chosen garnish can add color, texture, and height, transforming a simple dish into a visually stunning one that enhances the overall dining experience.

In contrast, the other options do not accurately reflect the purpose of a garnish. While adding weight to food and making a dish harder to eat are not desirable outcomes in culinary presentation, cooling down food is also unrelated to garnishes, which typically complement and enhance rather than alter the dish's intended temperature. Therefore, enhancing visual appeal is the primary and correct focus of a garnish's contribution.