Consider the market for cars. Which determinant of supply is affected by each of the following events? Choose from: prices of related goods, technology, prices of inputs, expectations, and the number of sellers in the market.
a. A steel tariff increases the price of steel.
b. Improvements in robotics increase efficiency and reduce costs.
c. Factories close because of an economic downturn.
d. The government announces a plan to offer tax rebates for the purchase of commuter rail tickets.
e. The price of trucks falls, so factories produce more cars.