The diagram below shows the market supply curve for commercial drone delivery services shifting from S1 S_1\,S1 to S2S_2S2.
Which of the following is most likely to have caused the shift from S1 S_1\,S1 to S2S_2S2?
A decrease in the market price of drone delivery services.
An increase in the cost of commercial liability insurance for drone operators combined with the withdrawal of a government subsidy for green logistics.
A technological breakthrough in battery manufacturing that lowers the production cost of long-range drones.
An increase in the market price of road-freight courier services, which are a substitute for drone deliveries.
