Answer : 4. "0.50 MAF"
Explanation :

1. Sprinkler irrigation system has been made mandatory for the first time in Rajasthan in the Narmada Canal Project.

2. Narmada Canal Project is between Gujarat, Rajasthan, Maharashtra, Madhya Pradesh.

3. This project is also known as Bhagirathi of Marwar.

4. It is completely based on sprinkler irrigation method.

5. The districts of Rajasthan benefited from Narmada Canal Project are Jalore-Barmer.

6. The total length of Narmada Canal Project is 532 km.

7. Rajasthan's total share in Narmada Canal Project is 0.50 M.A.F.

8. Sardar Sarovar Dam is used for the Narmada Canal Project.

9. The total length of the Narmada Canal Project is 532 km of which 458 km is in Gujarat and 74 km in Rajasthan.