Final answer:
To create an illustration for both a presentation and a web page, one should use graphics software, which offers tools for creating scalable and detailed images suitable for various media.
Step-by-step explanation:
To create an illustration that will be inserted into a presentation and will also appear on your company's web page, the appropriate software to use would be C) Graphics software.
Graphics software such as Adobe Illustrator or CorelDRAW is designed for creating and editing images, illustrations, and artwork that can be scaled to various sizes, making it ideal for both presentations and web graphics.
Diagramming software is more focused on creating structured diagrams, while presentation software is best for compiling and displaying slides for presentation purposes and may not have the robust graphic design features required. A fax machine is clearly irrelevant to this task.
The software you would use to create an illustration that will be inserted into a presentation and appear on your company's web page is graphics software.
Graphics software, such as Adobe Illustrator or CorelDRAW, allows you to create and modify images, illustrations, and graphics. It provides a wide range of tools and features to create visually appealing and professional-looking illustrations that can be exported in various formats, including image files compatible with presentations and web pages.