Which one among the following is not a west-flowing river?

Which one among the following is not a west-flowing river?

Mahi
Banas
Luni
Sabarmati
This question was previously asked in
UPSC CISF-AC-EXE – 2024
Most peninsular rivers in India flow eastwards into the Bay of Bengal, primarily due to the general eastward slope of the Deccan Plateau. However, some prominent rivers flow westwards into the Arabian Sea, including the Narmada and Tapti, which flow through rift valleys. Other west-flowing rivers listed in the options are Mahi, Luni, and Sabarmati, which drain into the Arabian Sea or the Rann of Kutch. The Banas River is a major river in Rajasthan. It is a tributary of the Chambal River, which itself is a tributary of the Yamuna River. The Yamuna joins the Ganges, which flows eastwards into the Bay of Bengal. Therefore, the Banas River is not a west-flowing river; it flows generally northeast/east before joining the Chambal.
The Banas River is a tributary of the Chambal, which flows towards the east-draining into the Bay of Bengal system, unlike Mahi, Luni, and Sabarmati which are west-flowing rivers.
The Luni river is unique among the options as it is an inland river; it flows into the Rann of Kutch and does not reach the Arabian Sea. The Mahi River flows through Madhya Pradesh, Rajasthan, and Gujarat, and drains into the Arabian Sea. The Sabarmati River originates in the Aravalli Range of Rajasthan and flows southwest across Gujarat into the Arabian Sea.