Which district in Tamil Nadu has the largest share of forest?
Erode district in terms of area. (2307 sq km)
Nilgiris district in terms of percentage. (67%)
Both are neighboring districts. Their adjoining districts like Coimbatore and Salem, Krishnagiri and Dharmapuri also has higher forest cover. Overall Kongu districts has high % of forest cover since they fall in western ghats.
Delta districts has negligible forest cover since farming has destroyed all the forests and wild life several centuries ago.
Hence option C is correct.