Statement I: The price of vegetables has increased significantly in the last month.
Statement II: There were unseasonal heavy rains across the country last month, damaging crops.

Statement I defines the event that the price of the crops has increased significantly in the last month. A price increase can be caused by a rise in demand or a decrease in supply. Statement II outlines that unseasonal heavy rains in the previous month have damaged the crops; it follows that this might have led to a reduction in the supply of the crops. The most suitable answer, therefore, is option B. Statement II is the cause and statement I is its effect.