Which type of line is described as thin and unbroken, indicating the ends of a measured distance?

• A. Visible line
• B. Extension line
• C. Dimension line
• D. Hidden line

Answer: (B)

The correct choice is indicated by the term that describes a line representing the ends of a measured distance on a technical drawing or blueprint. An extension line is used to extend a feature from the drawing to the dimension line, which specifically indicates where the measurement begins and ends.

In this context, extension lines typically appear thin and unbroken, serving to highlight or point to the dimensions of the object being illustrated, but they themselves do not contain the measurement. By connecting to the features of the object, extension lines allow for clear communication of dimensions to anyone reading the drawing, ensuring that the measurements are easily understood.

The other types of lines mentioned have different functions: visible lines outline the contours of an object; hidden lines represent features that are not visible from the specific view (often depicted as dashed lines); and dimension lines indicate the actual measurement and are usually accompanied by numerical values. Understanding these distinctions is crucial for interpreting technical drawings accurately.