Answer : 3. "They prevent the monsoons from crossing to the north and also serve as a reservoir of water from which our perennial rivers flow"
Explanation :

Answer: C) They prevent the monsoons from crossing to the north and also serve as a reservoir of water from which our perennial rivers flow Explanation: (a) refers to political importance and (b) to economic importance. Out of (c) and (d), (c) is more important.