What tool is used to adjust the spacing between letters in a selected area of text?

The correct choice is based on the function of adjusting the spacing between letters in a selected area of text, known as tracking. Tracking refers to the uniform adjustment of space between all characters in a word or a selection of text. This adjustment affects the overall density and visual balance of the text, allowing for more control over how text appears, especially in design-heavy applications like Adobe After Effects.

Kerning, while often confused with tracking, specifically refers to the adjustment of space between individual letter pairs to achieve a more visually pleasing result. It targets specific letters rather than applying a uniform adjustment across a selection, making it distinct from tracking.

The term "Letter Spacing Tool" is not a standard term within After Effects for adjusting text spacing, which can lead to confusion. Similarly, "Text Adjuster" does not specifically refer to a particular tool or function for adjusting letter spacing in the software. Therefore, tracking is the most accurate choice for adjusting the spacing between letters in a selected area of text, making it the correct answer.