Answer: The correct answer is d. automatic stabilizers.
Explanation: Automatic stabilizers are provisions in the budget that cause government spending to rise or taxes to fall without requiring new legislation when the economy experiences a downturn, such as a decrease in GDP. These provisions are designed to stabilize the economy by providing an automatic boost to aggregate demand during times of economic weakness. They help to mitigate the negative effects of economic downturns and provide a degree of stability to the overall economy without the need for discretionary policy changes.