XML validated against a DTD is "Well Formed" XML
B
Correct answer
Explanation
There's a distinction between 'well-formed' XML (correct syntax) and 'valid' XML (well-formed + conforms to DTD/schema). A document can be well-formed without being validated against a DTD. Validating against a DTD makes it 'valid' XML, not just 'well-formed' - it must already be well-formed to even be validated.