Part $1$

Explain how a$$ downward$-$sloping demand curve results from consumers adjusting their consumption choices to changes in price.

Part $2$

A$.$

When the price of a good rises$,$ the budget constraint shifts$$ outward, leading consumers to buy less of that good.

B$.$

When the price of a good$$ declines, this causes positive substitution and income$$ effects, leading consumers to buy more of that good.

C$.$

When the price of a good declines$,$ the marginal rate of substitution$$ changes, leading consumers to buy more of that good.

D$.$

When the price of a good$$ rises, this causes a negative income effect that is larger in absolute value than a corresponding positive substitution$$ effect, leading consumers to buy less of that good.

E$.$

When the price of a good declines$,$ the ratio of the marginal utility to price rises$,$ leading consumers to buy more of that good.