Q. Which of the following drainage systems drains the lands of Bihar ?

Correct Answer: a) Ghagra

Explanation:
The state of Bihar is primarily drained by rivers that are part of the Ganga River system. The Ghagra River is one of the major tributaries of the Ganga and flows through parts of Bihar, contributing to its drainage system.

– Mahanadi: This river flows through central and eastern India, primarily in Chhattisgarh and Odisha, and does not affect Bihar.
– Yamuna: This river flows through northern and central India, primarily in states like Uttarakhand, Uttar Pradesh, Haryana, and Delhi, but not Bihar.
– Narmada: This river flows westward through central India, mainly in Madhya Pradesh and Gujarat, and does not drain Bihar.

Thus, the correct answer is Ghagra, as it is part of the Ganga River system that drains the lands of Bihar.