What is the function of a primer in automotive body repair?

The function of a primer in automotive body repair is primarily to promote adhesion of paint and protect against rust. Primers serve as a preparatory layer that enhances the bonding of subsequent paint layers to the surface of the vehicle. This is crucial because a good bond between the primer and the paint ensures a more durable finish, reducing the risk of peeling or flaking over time.

Additionally, primers often contain rust-inhibiting properties that provide a barrier against moisture and environmental factors that can cause corrosion. By sealing the surface and creating a protective layer, the primer helps preserve the integrity of the metal beneath. This is especially important in automotive applications, where exposure to various elements can lead to rusting if not adequately protected.

While primers can indeed provide a base color to some extent and ensure a more uniform final appearance, their essential role lies in adhesion and rust protection, making choice B the most accurate representation of primer function in automotive body repair. The other options, although they might seem relevant in different contexts, do not capture the primary purpose of primer in this specific application.