Final answer:
For a client with a protruding chin, the ideal hairstyle should have fullness at the top and crown to balance facial features. Volume at the sides may also contribute to a more harmonious appearance.
Step-by-step explanation:
For a client with a protruding chin, characterized by a prominent mental protuberance, which is the forward projection at the inferior margin of the anterior mandible that forms the chin, you should create a hairstyle with fullness at the top and crown of the head. This can help to balance the features by bringing the eye upwards and creating an illusion of a more balanced facial structure. Additionally, hairstyles that add volume at the sides can also help to minimize the appearance of a protruding chin by creating a greater sense of width in the upper portion of the face.