Which of the following best defines the term 'tracking' in typography?

Tracking in typography specifically refers to the uniform adjustment of space between characters in a given section of text. This is done to optimize readability and improve the overall appearance of the type. By manipulating character spacing, tracking can alter how crowded or spaced out the text appears, which is particularly useful in achieving a desired aesthetic or fitting text within a specific design layout.

The other options presented focus on different aspects of text formatting. Line spacing involves the vertical space between lines, while paragraph spacing pertains to the space above and below a paragraph itself. Adjusting font size is about scaling the characters in height, without directly affecting the space between them. Each of these elements is vital for effective typography but does not define tracking, which is why tracking is solely concerned with character spacing adjustments.