UPSC CSE Prelims
Question 47
Consider the following assertion:
In the Pleistocene period either the Yamuna once flowed into the Indus, or the Sutlej flowed into the Yamuna and one major tributary of either had shifted from the Ganga to the Indus or vice versa.
Which of the following is/are the basis of the above assertion?
- The Nadi-Sukta of the Rigveda
- The explorations of the Sutlej and the Yamuna by Robert Bruce Foote
- The presence of the same species of dolphins in both the Indus and the Ganga river systems
Select the answer using the code given below:
View correct answer and explanation
Correct answer: D
Correct Option: D
Explanation: The freshwater Indus and Ganges river-dolphin populations offer biogeographic clues to older connections or river-capture events between the two drainage systems.
Statement-wise Analysis:
Statement 1: Incorrect - A river list in a Vedic hymn does not by itself demonstrate a Pleistocene river capture.
Statement 2: Incorrect - The named historical exploration is not decisive scientific evidence of this ancient drainage link.
Statement 3: Correct - Closely related freshwater river dolphins in the two systems offer evidence consistent with an earlier hydrological connection.
Option-wise Analysis:
A: Incorrect - Includes unsupported item(s) 1 and omits supported item(s) 3.
B: Incorrect - Includes unsupported item(s) 2 and omits supported item(s) 3.
C: Incorrect - Includes unsupported item(s) 1, 2 and omits supported item(s) 3.
D: Correct - This option includes the supported item(s) and excludes the unsupported ones.
Review note: River-dolphin taxonomy and palaeodrainage reconstructions are contested; treat the inference as evidence consistent with-not proof of-a particular channel switch.