Answer:
The correct answer is letter "B": Increase output and hire more workers.
Explanation:
According to the supply law, if the price increases so will the quantity supplied and if the price decreases the same will happen with the quantity supplied. We could say that the relationship between price and quantity supplied is directly proportional.
In the example, as the price of coal increased so will the quantity supplied. If there is to be more supply the output should be higher which is likely to be interpreted in a need for more employees.