The owner of a large car dealership believes that the financial crisis decreased the number of customers visiting her dealership. The dealership has historically had 800 customers per day. The owner takes a sample of 100 days and finds the average number of customers visiting the dealership per day was 750. Assume that the population standard deviation is 350.1. The population parameter to be tested is .a) the mean number of customers visiting the dealership per dayb) the average number of 750 customers per dayc) the standard deviation of the number of customers visiting the dealership per dayd) the proportion of customers visiting the dealership per day