Explanation
Why Correct: The Indira Gandhi Canal Project irrigates over 6.7 million hectares across Rajasthan and Punjab, making it India's largest irrigation project by command area.
Distractor Analysis: Bhakra-Nangal Project irrigates about 4 million hectares across Punjab, Haryana, Rajasthan, and Himachal Pradesh. Damodar Valley is primarily a multipurpose river valley project focused on flood control and power generation in Jharkhand and West Bengal. Nagarjunsagar Project irrigates about 1.2 million hectares in Andhra Pradesh and Telangana. Rihand Project is a major hydroelectric and irrigation project on the Rihand River in Uttar Pradesh.
Takeaway: Sardar Sarovar Project is the largest dam by volume in India, while Bhakra Dam is the second highest gravity dam in Asia.