What is the primary purpose of a base coat in nail care?

The primary purpose of a base coat in nail care is to protect the natural nail from staining. When colored nail polish is applied directly to the nail, especially darker shades, it can lead to discoloration or staining of the nail plate. A base coat creates a barrier between the nail and the pigment in the polish, effectively preventing this staining from occurring. Additionally, base coats can improve the adhesion of the polish to the nail, which can enhance the longevity of a manicure.

While other options may describe different nail care products or purposes, they do not accurately represent the main function of a base coat. For instance, adding color is the role of colored nail polish rather than a base coat. Creating a shiny finish is typically associated with a top coat, which is applied after the colored polish. Removing old polish is a task for a nail polish remover and is not related to the purpose of a base coat.