What is the primary purpose of a band saw?

The primary purpose of a band saw is to make curved cuts and resaw lumber, which makes option B the correct choice. Band saws are equipped with a long, continuous toothed blade that allows for precise and intricate cuts. This design enables them to slice through wood effectively, following complex curves or shapes that would be challenging with a straight cutting tool.

In addition to making curved cuts, band saws are also used for resawing, which involves cutting lumber into thinner boards. This versatility is particularly beneficial in woodworking and cabinetmaking, where customized shapes and sizes are often needed. The ability to adjust the blade height and tension further enhances the band saw's capability for various cutting techniques.

Other options like making straight cuts in wood, drilling holes, or sanding surfaces do not capture the distinct features and common uses of the band saw. While straight cuts can be made with a band saw, other tools are typically more efficient for that purpose. Similarly, drilling and sanding functions are specialized tasks better suited to other tools, making option B the most accurate representation of the band saw's primary function.