What is the U.S. standard unit of measurement when measuring the length of a piece of wood?

The U.S. standard unit of measurement for the length of a piece of wood is the inch. This choice is widely accepted in the United States for various applications, especially in construction and woodworking. Measurements in inches are commonly used for wood dimensions, such as the thickness of boards and the width of cuts.

The inch offers a practical level of precision for both professionals and DIY enthusiasts, making it ideal for projects that require an accessible, straightforward measurement system. Other units like the meter and centimeter are part of the metric system, which is more commonly used in many parts of the world but less so in the context of woodworking in the U.S. The yard, while also a unit of length used in the U.S., is typically applied to larger measurements and is not standard for describing the dimensions of smaller wooden pieces. Thus, among the choices provided, inch is the most relevant and widely utilized unit for this context.