What is the function of a planer?

The function of a planer is to smooth and flatten wooden surfaces, making option B the correct choice. A planer is a woodworking tool designed to remove material from the surface of wood, ensuring uniform thickness and a smooth finish. This process is essential for preparing wood for joinery, finishing, or other uses by providing a clean surface that can easily accept paint or stain.

Planers are typically used in woodworking environments to achieve the desired dimensions for boards and panels. By removing small amounts of material from the surface, they help produce flat and level surfaces, which are critical for quality woodworking projects. This capability distinguishes the planer from other tools that serve different purposes, such as drilling or measuring, which do not contribute directly to surface finishing in the same way.