Yang Manufacturing makes a product called Yin. The relevant range of operations is between 2,500 units and 10,000 units of Yin per month. Per unit costs at two activity levels are as follows: 5,000 units at $17.00 per unit; 7,500 units at $13.00 per unit. Determine the cost formula that expresses the behavior of Yang’s total costs (Y):

a. Y = $20,000 + $13X

b. Y = $45,000 + $4X

c. Y = $40,000 + $9X

d. Y = $60,000 + $5X

e. Y = $50,000 + $4X