A request omits Accept-Encoding entirely. Another sends Accept-Encoding with an empty field value. How do the two differ?
Omitting it means identity only, while an empty value means any coding is acceptable
They are equivalent; both mean identity only
Omitting it means any content coding is acceptable, while an empty value means no content coding is wanted✓الإجابة الصحيحة
An empty field value is invalid and must be rejected with 400 (Bad Request)
الشرح
Absence of the field signals no preference at all, so any coding is acceptable, whereas an explicitly empty value is a positive statement that the user agent wants no content coding in the response. The two are opposites, which is easy to invert in an implementation.