Detailed Explanation:

✅ Mahanadi River Valley – Correct: Extensive coal reserves in Odisha and Chhattisgarh, including the Talcher and Ib River coalfields.
✅ Damodar River Valley – Correct: Known as the "Ruhr of India", contains major coalfields like Jharia, Raniganj, and Bokaro in Jharkhand and West Bengal.
✅ Son River Valley – Correct: Significant coal deposits in Madhya Pradesh and Chhattisgarh, including the Sohagpur and Johilla coalfields.

All three river valleys are rich in Gondwana coal reserves, making "More than one of the above" the correct answer.