What must be added first to create a section view in a drawing?

To create a section view in a drawing, the first step is to establish a cutting plane, which is a graphical representation indicating where the view will be "cut" to reveal the interior details of the object. This cutting plane serves as a guideline for generating the section view, indicating the specific area of the object that will be illustrated and displayed in detail. Without this crucial element, there would be no basis for the section view, rendering it impossible to effectively showcase the internal features of the part being represented.

The other options may play a role in the overall drawing but are not the foundational step for creating a section view. For instance, a section line is used to indicate where the cut takes place but comes after defining the cutting plane. A cut list relates to inventory or parts management and is not relevant to section views. An isometric view provides a different perspective of the object entirely and does not contribute to the process of creating a section view. Thus, starting with a cutting plane is essential for accurately depicting the internal elements in a section view.