The correct answer is option 1, Luni. The Luni River is the only one among the given options that drains into the Rann of Kutch.

Option 2, Mahi River, is not correct. The Mahi River is a river in western India that flows through the states of Madhya Pradesh, Rajasthan, and Gujarat, but it does not drain into the Rann of Kutch.

Option 3, Narmada River, is also not correct. The Narmada River is a major river in central India that flows through the states of Madhya Pradesh, Maharashtra, and Gujarat, but it also does not drain into the Rann of Kutch.

Option 4, Sabarmati River, is not correct either. The Sabarmati River is another river in western India that flows through the state of Gujarat, but it does not drain into the Rann of Kutch.

Therefore, the only river among the given options that drains into the Rann of Kutch is the Luni River.