Which of the following tool enables you to add text to a slide without using the standard placeholders?

The tool that enables you to add text to a slide in PowerPoint without using the standard placeholders is Option A: Text tool box. This tool allows you to create a text box anywhere on the slide, independent of the predefined text placeholders that are typically part of slide layouts.
Option B: Line tool is used to draw lines and shapes on slides.
Option C: Drawing tool is a generic term that could refer to various drawing and shape tools in PowerPoint.
Option D: Auto shapes tool is used to quickly insert predefined shapes such as rectangles, circles, arrows, etc., into slides.
Therefore, the correct answer in this context is Option A: Text tool box.