A lawn-service company charges a customer $ 60 for each time that they visit that customer in order to maintain the customer's lawn. In a month, the company works x days. The company is able to maintain n laws per day. The company's profit for the entire month is P = 60nx - 450x. In this equation, what is the best explanation for the meaning of the coefficient 450? A-n represents the total number of water bottles for A the entire month.

B-n represents the total number of water bottles in one shipment.

C-n represents the total weight of one shipment.

D-n represents the total number of shipments in one month.