People need to have in the economy to spend money.
a.) purchasing power
b.) confidence
c.) less disposable income

Purchasing power is required in order for someone to spend money. Purchasing power means that someone has the ability to purchase something (a product or service). Having confidence is not enough to allow you to purchase something. You can't walk into a store with no money or goods to barter and walk out with the product or service. Less disposable income is more likely to lead to less purchasing power. In order to purchase something, you need to give up something in order to get what you want, generally you give up money. If you don't have something you can easily give up, like money, you have less disposable income.

So you know what happened and so it doesn’t repeat it’s self

Ithink the answer is d.