Final answer:
A highlight is appropriate when drawing reflective objects like glass or metal. It is a small, bright area that results from the reflection of light. The highlight is created due to the smooth surface of the object and the phenomenon of specular reflection.
Step-by-step explanation:
A highlight is appropriate when drawing objects that are very reflective, like glass or metal. When light hits a reflective object, it bounces off and creates a bright spot or highlight. This occurs because the surface of the object is smooth and allows for specular reflection, where light reflects at equal angles. The highlight is usually depicted as a small, bright area on the object.