Correct option is A
Final paragraph (BACD):
Rainwater harvesting is a simple conservation method. It helps in storing water for future use. This collected water can be used for daily needs. This method is especially useful in drought-prone areas.
Why BACD works:
· B introduces the topic.
· A follows naturally: “It” refers to rainwater harvesting and states the key benefit (storage).
· C specifies an immediate application of the stored/collected water (daily needs).
· D closes with the situational significance (drought-prone areas), giving the paragraph purpose and scope.