Correct option is B
According to BIS SP 46:2003, different types of lines are standardized in engineering drawings so that drawings can be universally understood without ambiguity. Among these, the chain thin line (also called a long dash–short dash pattern) has a very specific and important application.
A chain thin line is primarily used to represent center lines, axes of symmetry, pitch circles, and paths of motion. These lines help in identifying the geometric center of circles, cylinders, holes, and symmetrical components. For example, when drawing a shaft or a circular hole, the center line ensures proper alignment and dimensioning, which is critical in manufacturing and assembly.
