The correct answer is: a. Awa Lahaul valley.
The Awa River is a river in Himachal Pradesh, India. It originates in the Lahaul valley and flows into the Chenab River. The Luni River is a river in Rajasthan, India. It originates in the Aravalli Range and flows into the Arabian Sea. The Markanda River is a river in Haryana, India. It originates in the Shivalik Hills and flows into the Yamuna River. The Bata River is a river in Himachal Pradesh, India. It originates in the Spiti valley and flows into the Chenab River.
The Awa River is the only river in the list that originates in the Lahaul valley. The other rivers originate in different valleys.