If you buy less clothing because the price of clothing at your favorite store has gone up, what has happened?

The purchase and sale of goods and services is managed by the mechanisms of supply and demand in a market economy. The mechanism for adjusting supply and demand is price. If the price has risen and you have stopped buying, demand will be lower and in the future the store will have to lower prices again unless other consumers are willing to pay a high price. Another important element is scarcity. If the good becomes scarce, as when a store sells its stocks, the price of the remaining merchandise tends to rise.

d. i assume the underlined word is "role." reformat if it isn't.

explanation:

role is closest to part because when replacing words, "playing a vital decision," "playing a vital activity," and "playing a vital dollar" don't make logical sense. the only meaningful choice is "playing a vital part."

this fits one of merriam-webster's definitions of role: "a function or part performed especially in a particular operation or process."