Assume a profit-maximizing firm in a perfectly competitive market. To produce, it needs a machine, and each it it operates the machine it needs a worker and some electricity. In 2020, it produced q20 units. In 2021, its the amount it paid to rent the machine decreased by $10,000 and it produced q21 units. Which of the following is true the only thing in the world that changed was the price this firm paid to rent a machine? O MC(q21)> MC(q20). Variable costs were higher in 2021 than in 2020. MC(q21)>MC(q20). Variable costs were lower in 2021 than in 2020. ( MC(q21)