Correct option is D
Event (ii): The government reduced the tax on importing goods. → Cause
When import tax is reduced, it directly causes a drop in the price of imported goods.
So, event (ii) (reduction in tax) is the cause, and event (i) (price drop) is the effect.
Thus, the correct option is (d) Event (i) is the effect and event (ii) is its immediate and principal cause.