Question

Identify the ‘a’ in the below given picture.

(a) dimension line

(b) outline

(c) leader

(d) extension line

The question was posed to me in a national level competition.

This is a very interesting question from Terminology of Dimensioning topic in portion Lines, Lettering and Dimensioning of Engineering Drawing

Answer 1

Right choice is (d) extension line

For explanation I would say: An extension line also a thin continuous line drawn in extension of an outline. It extends by about 3 mm beyond the dimension line. Dimension line is a thin continuous line. It is terminated by arrowheads touching the outlines, extension lines or centre lines.