Which of the following rivers is the last left bank tributary of the Ganga in West Bengal?

The correct option is The Mahananda.

Explanation

The Ganga river system is fed by numerous tributaries from the Himalayas (left bank) and the Peninsular plateau (right bank). Understanding the east-west sequence of these tributaries is essential for mapping the drainage system.

Detailed Analysis:

• The Mahananda: It rises in the Darjeeling hills of West Bengal. It flows southwards and joins the Ganga on its left bank. It is the last major left-bank tributary of the Ganga in West Bengal before the main river enters Bangladesh (where it is known as the Padma).
• The Damodar: It rises in the Chotanagpur Plateau and flows through a rift valley. It joins the Hooghly (a distributary of the Ganga) on its right bank, south of Kolkata. It is not a left-bank tributary of the main Ganga.
• The Kosi: It is a major left-bank tributary that rises in Tibet. However, it joins the Ganga in Bihar, which is located upstream relative to the confluence of the Mahananda.
• The Tista: It rises in Sikkim and flows through West Bengal, but it is a tributary of the Brahmaputra (Jamuna) in Bangladesh, not the Ganga.

Key Takeaway: The Mahananda is the easternmost and the last left-bank tributary of the Ganga river system within Indian territory.