Alarge new diamond mine has just opened and the price of diamonds has gone down. since she has studied economics, cecilia decides to buy a diamond necklace since she knows that

If the supply increases the price decreases.

Explanation:

If the supply of diamonds increases the price decreases. In fact, one of the reasons why diamonds are very expensive is because it is a scarce commodity in the world and also its extraction and production process has a high cost.

Cecilia can afford to acquire the diamond necklace by the opening of the new mine since the price has decreased and she knows that being a non-renewable resource, when the mine runs out the price of diamonds will rise again and she could sell her necklace and get a profit.

elastic potential energy

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."