Final answer:
The major source of water for Indus civilizations was monsoon rains.
Step-by-step explanation:
The major source of water for Indus civilizations was monsoon rains. The Indus Valley region experienced an annual monsoon season, during which heavy rainfall would occur. This rainfall would replenish the rivers and create an abundant water supply for the civilizations.
While irrigation ditches were used to divert water from the rivers to agricultural fields, they were not the major source of water. The Arabian Sea was an important water route for trade and transportation but was not a direct source of water for the civilizations. Deep wells were also used to access groundwater, but they were not the primary source of water.
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