Final answer:
A positive supply shock, such as a decrease in the price of oil, will lead to a decrease in the price level and an increase in output.
Step-by-step explanation:
A positive supply shock, such as a decrease in the price of oil, is most likely to have the following short-run effects:
a) Price level: Decrease / Output: Increase
When the price of oil decreases, it leads to a decrease in production costs for businesses, which allows them to produce goods and services at a lower cost. This increase in supply leads to a decrease in the price level and an increase in the output of goods and services.