Explanation:

- Option 1: Godavari

The Godavari River is the second longest river in India.

Its basin primarily lies in Maharashtra, making up about 50% of it.

This is the correct option.

- Option 2: Kaveri

The Kaveri River primarily flows through Karnataka and Tamil Nadu.

It doesn't significantly impact Maharashtra.

- Option 3: Mahanadi

The Mahanadi River mainly flows through Chhattisgarh and Odisha.

Maharashtra is not a primary region of the Mahanadi basin.

- Option 4: Narmada

The Narmada River flows through central India, notably Madhya Pradesh and Gujarat.

It does not significantly contribute to Maharashtra's basin.