Answer:
The correct answer is letter "D": positive supply.
Step-by-step explanation:
A supply shock occurs when an unexpected event changes the supply of a good or service which changes the price of that product. When the supply shock is positive, the supply increases and the price decreases. If the supply is negative, the supply decreases and the prices increase.
Thus, if the costs of health insurance decrease, expecting an increase in the supply in health insurance, the supply shock will be considered positive.