Which statement about validating markup is true?

Which statement about validating markup is true?

• A. Validation always passes when code is well-formed.
• B. Validation depends on external resources.
• C. If a validator finds an error, the remaining code on the page may fail validation, even if the remaining code is actually valid.
• D. Validation errors only occur in HTML attributes.

Answer: (C)

Validation checks that markup follows the rules defined by the HTML specification, not just that it is well-formed. A document can be well-formed but still invalid if it uses elements or attributes in ways the spec disallows, or if it relies on deprecated structures. A single mistake early in the document can change how the rest is parsed, so the validator may flag code later on even if that later code would be valid when read in isolation. For example, a missing closing quote on an attribute or an unclosed tag can cause the parser to treat the following content differently, leading validation errors down the line. External resources aren’t the defining factor for validity; validators can work with the document alone, though some might fetch DTDs or schemas. And errors aren’t limited to attributes; they can involve structure, nesting, and usage of elements as well. So the statement about the remaining code potentially failing validation because an earlier error was found best captures how validation works.