Rainwater Harvesting

(1) Globally, water shortages have become a major cause for concern. (2) Although water covers about 71 percent of Earth's surface, people face water scarcity. (3) Out of this total, only 3 percent is fresh water, 2.5 percent of which is in the form of glaciers. (4) Therefore, people need to manage and distribute fresh water that is available effectively. (5) According to recent research, nearly one billion people across various nations do not have access to clean drinking water.
(6) To combat this water scarcity, many nations have begun rainwater harvesting. (7) Many societies have been practicing the technique of rainwater harvesting, but the recent water shortage has inspired people in urban areas to implement it as well. (8) Rainwater harvesting is the practice of collecting and storing rainwater for agricultural and domestic use. (9) Instead of letting rainwater fall off their roofs, people collect the water in huge water storage tanks. (10) The stored water is usually used for irrigation or gardening. (11) If people want to use the stored water for domestic purposes such as drinking or cooking, the water needs to be purified.

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Which detail would be best to add after sentence 3 to develop the topic?
A.
Glaciers are only formed in very cold climates.
B.
Most people do not live near glaciers to get water from them.
C.
Water frozen in glaciers cannot be accessed by the global population.
D.
Glaciers sometimes melt at a rapid ra