Within the river systems of India, which one of the following rivers is recognised as the longest river of peninsular India?

Introduction / Context:
India has several major river systems, and questions in geography often ask about the longest or most important rivers in different regions. The term peninsular India refers to the southern part of the country that extends into the Indian Ocean. Among the rivers originating and flowing largely within this peninsular region, one is known as the longest. This question tests basic river geography by asking which river holds that distinction.

Given Data / Assumptions:
- The focus is on peninsular India, not the entire Indian subcontinent. - Options provided are Narmada, Godavari, Mahanadi and Cauvery. - We need to identify which river has the greatest length within this group. - Length is considered along the main course of the river.

Concept / Approach:
In standard geography references, the Godavari River is described as the longest river of peninsular India. It is sometimes called the Dakshin Ganga or Ganga of the South because of its length and importance. The Narmada flows westward but is shorter than Godavari. Mahanadi and Cauvery are also major peninsular rivers but have shorter courses. Hence, the approach is to recall the approximate lengths and relative importance of these rivers and select Godavari as the longest.

Step-by-Step Solution:
Step 1: Recall that Godavari originates in the Western Ghats in Maharashtra and flows eastward across several states before entering the Bay of Bengal. Step 2: Remember that geography textbooks frequently describe Godavari as the longest river of peninsular India, with a length of over 1400 kilometres. Step 3: Compare this with Narmada, which, although significant, is shorter and flows mainly through Madhya Pradesh and Gujarat. Step 4: Note that Mahanadi and Cauvery are also shorter than Godavari in total length. Step 5: Based on these comparisons, select Godavari as the correct answer.

Verification / Alternative check:
To verify, one can consult standard maps and tables in geography guides that list major Indian rivers and their lengths. These tables consistently rank Godavari as the longest among peninsular rivers. Narmada, Mahanadi and Cauvery are listed with lower lengths. Some guides also highlight that Godavari has a large basin and crosses multiple states, reinforcing its status as the longest peninsular river. This cross checking confirms that Godavari is the correct choice.

Why Other Options Are Wrong:
Narmada: Although Narmada is an important west flowing river, its length is less than that of Godavari, so it is not the longest peninsular river.
Mahanadi: Mahanadi is a major river in eastern central India but its total length is shorter than Godavari, which disqualifies it from being the longest.
Cauvery: Cauvery is a key river in southern India, but its length and basin area are both smaller than those of the Godavari River, so this option is also incorrect.

Common Pitfalls:
Learners sometimes confuse the most important river in a cultural or economic sense with the longest river. For example, Narmada or Cauvery may feel more familiar due to their religious or regional importance, leading to wrong choices. Another error is to mix up peninsular rivers with Himalayan or all India rivers such as the Ganga and Brahmaputra, which are longer but are not peninsular in the strict sense. To avoid confusion, it is useful to remember that within peninsular India, Godavari stands out as the longest river and is often called the Ganga of the South.

Final Answer:
The longest river of peninsular India is the Godavari River.