Which of the lines is a thin continuous line with the ends terminating in arrowheads and is enclosed by extension lines, outlines or centre lines?

Lines, Lettering and Dimensioning topics include: Different types of lines, system dimensioning, dimensioning types, dimensioning principles and terminology.

In engineering drawings, dimensioning is the process of adding numerical values to a drawing using lines, symbols, and notes. These values are used to define the size characteristics of an object, such as its length, height, breadth, diameter, radius, and angle. 
 

There are three types of dimensions for most objects: Size dimensions, Location dimensions, Notation dimensions.