In Cascading Style Sheets, what are the main parts of a CSS ruleset and how are they structured?

Introduction / Context:
CSS uses rulesets to describe how HTML elements should be displayed. Understanding the structure of a ruleset is fundamental for writing valid styles. Every CSS rule follows a clear pattern that browsers can parse: a selector targets elements, and a declaration block describes what visual changes to apply. This question checks whether you can identify those components and explain how they fit together.

Given Data / Assumptions:
- We are using standard CSS syntax as supported by modern browsers.
- A ruleset is written as selector followed by a block inside curly braces.
- Declarations are separated by semicolons inside the block.
- Each declaration affects one property of the selected elements.

Concept / Approach:
In its simplest form, a CSS ruleset looks like p { color: blue; }. Here, p is the selector, and the declaration block is { color: blue; }. Inside that block, color is the property and blue is the value. Multiple declarations can appear inside one block, each changing different aspects such as font size, margin, or background. The correct option must describe this structure of selector plus property value declarations.

Step-by-Step Solution:
Step 1: Recall that the selector identifies which elements will be styled. Step 2: Recognize that curly braces contain one or more declarations. Step 3: Understand that each declaration is written as property, colon, value, and end with a semicolon. Step 4: Select the option that clearly states that a ruleset includes a selector and a declaration block with property value pairs.

Verification / Alternative check:
Checking any CSS reference confirms this structure. Examples always show a selector followed by declarations between braces. If you remove the selector, the ruleset becomes invalid. If you remove properties or values, the declarations are incomplete. These observations support the chosen option as the correct explanation.

Why Other Options Are Wrong:
Option B is wrong because values without properties or selectors do not form a valid rule. Option C incorrectly equates CSS rulesets with Java classes, which belong to a different language. Option D is false because selectors alone do nothing without declarations. Option E is unrelated since file paths are part of HTML link tags, not CSS ruleset structure.

Common Pitfalls:
Common mistakes include missing semicolons, misspelled properties, or forgetting curly braces, all of which break the ruleset. Another pitfall is writing multiple selectors and declarations in a confusing way that makes styles hard to read. Keeping each ruleset simple and clearly structured helps improve maintainability and reduces errors.

Final Answer:
A CSS ruleset consists of a selector and a declaration block, and each declaration inside that block pairs a property with a value to style the selected elements.