question content area the production department is proposing the purchase of an automatic insertion machine. it has identified three machines and has asked the accountant to analyze them to determine the best average rate of return. which machine has the best average rate of return? machine a machine b machine c estimated average annual income $42,111.72 $63,068.40 $74,219.10 average investment $300,798.00 $210,228.00 $494,794.00 a.machine a or b b.machine a c.machine b d.machine c