The event that would shift a supply curve to the left is:
Local government increases the taxes that are levied on firms.
An increase in taxes on firms raises their costs of production, which typically leads to a decrease in supply, hence shifting the supply curve to the left.
The other options would not result in a leftward shift of the supply curve:
- The expectation of falling prices (second option) would not directly cause a leftward shift; it might lead firms to supply more in the short term in order to sell at higher current prices.
- An increase in the number of sellers (third option) generally shifts the supply curve to the right, as more sellers typically increase the total supply.
- A dramatic reduction in the prices of inputs (fourth option) would also lead to a rightward shift, as lower input costs make production cheaper and encourage firms to produce more.