The main cause of the Civil Disobedience Movement in 1930 was the protest against British monopoly on salt. Option 1 correctly identifies this cause. During this movement, Indians were outraged by the British government`s oppressive Salt Act, which allowed the British to control the production and sale of salt, an essential commodity. Mahatma Gandhi led the movement, encouraging Indians to break the law by producing and selling their own salt. This act of civil disobedience displayed the dissatisfaction of Indians towards British rule and their desire for self-governance. The movement gained widespread support and sparked further protests and acts of civil disobedience across the country. It was a significant moment in India`s struggle for independence.