Concept:The recognized classifications of Hadith are Sahih, Hasan, and Daif.
Explanation:Sahih means authentic, Hasan means good, and Daif means weak.
These three are the standard classes used for judging the authenticity and strength of a Hadith.
Mawdu means fabricated or forged, so it does not belong to the regular classification of Hadith.
It refers to a saying falsely attributed to the Prophet, not an accepted category in the main scheme.
Hence, the odd one here is Mawdu.
Answer:C. mawdu