Adepartment store's customer parking lot has 4 rows with an equal number of parking spots in each row. the lot also has 15 parking spots for store employees. if c cars can be parked in each of the 4 main rows of the parking lot, what is the expression for the maximum number of cars that can be parked in the parking lot? a.15c − 4 b. c(15 − 4) c.4c + 15 d.4(c + 15)