In MS Word 2010, a Quick Style is a named, reusable package of formatting stored in the Styles gallery. Word classifies these styles by the scope of text they act upon, and this scope is exactly what the question is testing. Understanding the difference helps you apply consistent formatting quickly and update an entire document by editing just one style definition.

The main Quick Style types in Word 2010 are:

• Character styles — Applied to selected characters or words only. They control character-level attributes such as font, size, bold, italic, underline, and colour, but they do not touch paragraph-level settings like alignment, indentation, or line spacing. Because they act on a selection, you can highlight a single word inside a paragraph and format it without disturbing the rest of the line.
• Paragraph styles — Applied to the entire paragraph in which the cursor sits (no selection needed). They carry both character formatting and paragraph formatting (alignment, indents, spacing, tab stops, borders).
• Linked styles — A hybrid that behaves as a paragraph style when the whole paragraph/cursor is targeted, but as a character style when only part of the text is selected.
• Page styles — Not a Microsoft Word concept at all; this is terminology from LibreOffice/OpenOffice Writer, so it can be dismissed immediately.

The question specifically asks for the style applied only to selected words or individual characters within a paragraph. That precise, character-level scope is the definition of Character styles, which is why it is correct. The choice describing formatting of the whole paragraph is wrong because it changes paragraph-level attributes and applies to the full paragraph, not a selection; the hybrid choice is wrong because it can behave either way rather than acting only on selected characters; and the page-based choice is wrong because Word 2010 has no such style type.