In Indian river system terminology, which river is popularly known as the "Vridha Ganga" or "Old Ganga" because of its large size and sacred importance in peninsular India?

Introduction / Context:
This question relates to Indian rivers and their traditional names and titles. Some rivers in India are given special epithets because of their size, course, or religious importance. The term "Vridha Ganga" or "Old Ganga" is often used in reference to a major peninsular river that is considered comparable to the Ganga in northern India in terms of its sacredness and length in the south.

Given Data / Assumptions:

• We are asked which Indian river is called "Vridha Ganga" or "Old Ganga".
• The options given are Krishna, Godavari, Kaveri, and Narmada.
• We rely on standard Indian geography and cultural references.

Concept / Approach:
The Godavari River is the longest river in peninsular India and flows through several states before draining into the Bay of Bengal. Due to its great length, large basin, and religious significance, it is often referred to as the "Dakshin Ganga" (Ganga of the South) and also "Vridha Ganga" (Old Ganga). These epithets reflect its status as a southern counterpart to the Ganga of northern India. The other rivers listed are also important but do not share this particular title.

Step-by-Step Solution:
Step 1: Recall the main rivers of peninsular India. Krishna, Godavari, Kaveri, and Narmada are all significant rivers in southern and central India. Step 2: Identify which of these is the longest peninsular river with a very large basin and many pilgrimage towns along its banks. The Godavari is the longest peninsular river and is considered highly sacred. Step 3: Remember that Godavari is popularly called "Dakshin Ganga" or "Ganga of the South" and also "Vridha Ganga". Step 4: Confirm that Krishna, Kaveri, and Narmada, while important, are not commonly referred to by this particular epithet. Step 5: Select Godavari as the correct answer.

Verification / Alternative check:
Geography and culture based sources describe Godavari as the second longest river in India after the Ganga and the longest river in the Deccan region. Numerous holy places such as Nashik and Rajahmundry lie along its course, and it holds a special place in Hindu tradition. This long length and sacred status are the main reasons it is likened to the Ganga and referred to as "Vridha Ganga". Other rivers, although revered, do not carry this specific title in standard references.

Why Other Options Are Wrong:
Option A, Krishna, is a major east flowing river but is not commonly called "Vridha Ganga". Option C, Kaveri, is known for its fertile delta and cultural importance in southern India but is not given this particular name. Option D, Narmada, is a west flowing river of central India and is associated with the Narmada Parikrama tradition, yet it is not generally called "Old Ganga". Only the Godavari, option B, is recognised by the epithets "Dakshin Ganga" and "Vridha Ganga".

Common Pitfalls:
Students sometimes confuse different traditional names such as "Dakshin Ganga", "Vridha Ganga", and nicknames associated with other rivers. Another mistake is to pick a river purely on the basis of name familiarity without recalling the specific epithets used in geography and culture. Associating each major river with one or two key facts or nicknames is a good way to remember them accurately.

Final Answer:
The river of India that is called "Vridha Ganga" or "Old Ganga" is the Godavari.