Mary owns a small business. She spent $4,500 to get the business started. She has noticed that her monthly operating costs have been consistent. After five months, she has spent a total of $5,250 in start-up costs and monthly operating costs. In a linear model of this situation, which of the following statements applies? A. An additional month of business operation is associated with an additional $50 in costs. B. An additional month of business operation is associated with an additional $150 in costs. C. An additional month of business operation is associated with an additional $750 in costs. D. An additional month of business operation is associated with an additional $500 in costs.